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Certain typographic errors & hyphenation inconsistencies +were silently corrected.</p> +<p class="p0">2. Illustration captions have been standardised.</p> +<p class="p0">3. Table of Contents extended by adding references +to the LIST OF ILLUSTRATIONS, INDEX, and ADVERTISEMENTS.</p> +</div> +<p><span class="pagenum" id="Page_1">[Pg 1]</span></p> + +<div class="chapter"> +<figure class="figcenter illowp45" id="cover" style="max-width: 143.5625em;"> + <img class="w100" src="images/cover.jpg" alt="Book cover: The Story of Life in the Seas" data-role="presentation"> +</figure> + +</div> + +<hr class="chap x-ebookmaker-drop"> + +<p><span class="pagenum" id="Page_2">[Pg 2]</span></p> + +<div class="chapter"> +<figure class="figcenter illowp53" style="max-width: 34.1875em;"> + <img alt="" class="w100" src="images/frontispiece.jpg" id="frontispiece"> +<figcaption><i>Frontispiece.</i><br><span class="smcap">A Jelly-fish with the fry of the Horse-mackerel</span><br> +(The fish have been relatively very much enlarged.)</figcaption> +</figure> +</div> + +<hr class="chap x-ebookmaker-drop"> + +<p><span class="pagenum" id="Page_3">[Pg 3]</span></p> + +<div class="chapter"> +<h1><span class="medium">THE</span><br> +STORY OF LIFE IN THE SEAS</h1> + +<p class="p0 center bold xlarge"> +<span class="small">BY</span><br> +<br> +<span class="large">SYDNEY J. HICKSON, D.Sc., F.R.S.</span><br> +<span class="small"><i>Professor of Zoology in the Owens College, Manchester</i></span><br> +<br> +<span class="medium"><i>WITH FORTY-TWO ILLUSTRATIONS</i></span><br> +<br> +<span class="medium">LONDON</span><br> +<span class="large">GEORGE NEWNES, LIMITED</span><br> +<span class="medium">SOUTHAMPTON STREET, STRAND</span><br> +<span class="small">1898</span><br> +</p> +</div> + +<p><span class="pagenum" id="Page_4">[Pg 4]</span></p> +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<p class="p0 center"> +OUTLINE CLASSIFICATION<br> +<span class='small'>OF</span><br> +ANIMALS MENTIONED IN THIS BOOK.<br> +</p> +</div> +<table class='bbox small outline'><tbody> + +<tr> +<td class="tdl" rowspan='2'>PROTOZOA</td> +<td class="tdl lines-2" rowspan='2'>⎧<br>⎨<br>⎩</td> +<td class="tdl">Foraminifers.</td> +</tr> +<tr><td class='tdl'>Radiolarians.</td></tr> + +<tr> +<td class="tdl">PORIFERA</td> +<td class="tdl"></td> +<td class="tdc">Sponges.</td> +</tr> + +<tr> +<td class="tdl" rowspan='4'>CŒLENTERATA</td> +<td class="tdl lines-4" rowspan='4'>⎧<br>⎪<br>⎨<br>⎪<br>⎩</td> +<td class="tdl">Sea-anemones.</td> +</tr> + +<tr> +<td class='tdl'>Corals.</td></tr> +<tr><td class='tdl'>Jelly-fish.</td></tr> +<tr><td class='tdl'>Many of the Zoophytes.</td> +</tr> + +<tr><td class="tdl">ECHINODERMA</td> +<td class="tdl lines-4">⎧<br>⎪<br>⎨<br>⎪<br>⎩</td> +<td class='tdl'> + <table class='tal'> + <tr> + <td class="tdl"><i>Asteroidea</i></td> + <td class='tdl pl1'>Star-fishes.</td> + </tr> + <tr><td class='tdl'><i>Echinoidea</i></td> + <td class='tdl pl1'>Sea-urchins.</td> + </tr> + <tr> + <td class='tdl'><i>Crinoidea</i></td> + <td class='tdl pl1'>Sea-lilies.</td> + </tr> + <tr> + <td class='tdl'><i>Holothuroidea</i></td> + <td class='tdl pl1'>Trepangs.</td> + </tr> + </table> +</td> +</tr> + +<tr><td class="tdl">PLATYELMIA</td> +<td class="tdl"></td> +<td class="tdl">Flukes, Tape-worms, Planarians.</td> +</tr> + +<tr><td class="tdl">CHÆTOPODA</td> +<td class="tdl"></td> +<td class="tdc">Segmented Worms and Gephyreans.</td> +</tr> + +<tr> +<td class="tdl">ARTHROPODA</td> +<td class="tdl lines-4">⎧<br>⎪<br>⎪<br>⎨<br>⎪<br>⎪<br>⎩</td> +<td class="tdl"> + <table class='tal'> + <tr> + <td class='tdl' rowspan='4'><i>Crustacea</i></td> + <td class="tdl lines-4" rowspan='4'>⎧<br>⎪<br>⎨<br>⎪<br>⎩</td> + <td class='tdl'>Copepods.</td> + </tr> + + <tr><td class='tdl'>Barnacles.</td></tr> + <tr><td class='tdl'>Shrimps.</td></tr> + <tr><td class='tdl'>Crabs.</td></tr> + + <tr> + <td class='tdl'><i>Insecta</i></td> + <td></td> + <td class='tdl'>Halobates, &c.</td> + </tr> + </table> +</td> +</tr> + +<tr><td class="tdl">MOLLUSCA</td> +<td class="tdl lines-3">⎧<br>⎪<br>⎪<br>⎨<br>⎪<br>⎪<br>⎩</td> +<td class='tdl'> + <table class='tal'> + <tr> + <td class='tdl'><i>Lamelli branchiata</i></td> + <td class='tdl pl1'>Bivalves.</td> + </tr> + <tr> + <td class='tdl'><i>Gastropoda</i></td> + <td class='tdl pl1'>Whelks, &c., and Pteropods.</td> + </tr> + <tr> + <td class='tdl'><i>Cephalopoda</i></td> + <td class='tdl pl1'>Octopuses, Cuttlefishes, &c.</td> + </tr> + </table> +</td></tr> + +<tr><td class="tdl">TUNICATA</td> +<td></td> +<td class="tdl">Sea-squirts, Salps, Pyrosoma.</td></tr> + +<tr> + <td class="tdl">VERTEBRATA</td> +<td class="tdl lines-4">⎧<br>⎪<br>⎪<br>⎪<br>⎨<br>⎪<br>⎪<br>⎪<br>⎩</td> + <td class='tdl'> + <table class='tal'> + <tr> + <td class='tdl'><i>Pisces</i></td> + <td></td> + <td class='tdl'>Fish.</td> + </tr> + <tr> + <td class='tdl'><i>Amphibia</i></td> + <td></td> + <td class='tdl'>Frogs.</td> + </tr> + <tr> + <td class='tdl'><i>Reptilia</i></td> + <td></td> + <td class='tdl'>Turtles, Crocodiles, Snakes.</td> + </tr> + <tr> + <td class='tdl'><i>Aves</i></td> + <td></td> + <td class='tdl'>Birds.</td> + </tr> + <tr> + <td class='tdl'><i>Mammalia</i></td> + <td class="tdl lines-3">⎧<br>⎪<br>⎨<br>⎪<br>⎩</td> + <td class='tdl'>Whales, Porpoises.<br> + Seals,<br> + and the terrestrial Mammals.</td> + </tr> + </table> +</td></tr> +</tbody></table> + +<hr class="chap x-ebookmaker-drop"> + +<p><span class="pagenum" id="Page_5">[Pg 5]</span></p> + +<div class="chapter"> +<h2 class="nobreak" id="PREFACE">PREFACE.</h2> +</div> + +<p>The story of the life of animals and plants in +the sea is one with so many aspects, that it is +difficult to choose the points that may be included, +and those that may be omitted from a book intended +for the general reader. To some the +story of the food Fishes and the Whales is of +the greatest interest; to others the beautiful +shapes and colours of shells have a predominating +fascination; and to those who have devoted +themselves to geological study, the history of +the animals that contribute to the formation of +the reefs and the ocean-bed present features of +special attraction. To many, then, the perusal +of my book must lead to disappointment as no +one of these aspects has been treated adequately; +but if some new interest is awakened, some new +train of thought quickened into life, one of the +objects I had in view will have been gained.</p> + +<p>The book is only intended to be a sketch of +some of the most important lines of scientific +researches which are now being pursued by +zoologists in many parts of the world. Discoveries, +which are of the deepest interest to +all intelligent minds, are in many cases described +in books and periodicals that do not come within +the reach of the general public. I have tried, +<span class="pagenum" id="Page_6">[Pg 6]</span> +therefore, to collect some of them into a small +compass and describe them in language which +I trust will be intelligible to those who have +not been trained in the alphabet of zoological +technicalities. The use of some long words was +unavoidable, but I have endeavoured to explain +them adequately either in the text or in the +index.</p> + +<p>Some of the illustrations have been copied +from the works of other Naturalists, and the +sources from which they came are acknowledged +in the list of illustrations; but the majority of +them have been drawn, specially for this work, +from specimens from the Manchester Museum +or my own collections.</p> + +<p class="p0 right"> +SYDNEY J. HICKSON.<br> +</p> + +<p><span style="margin-left: 2em;"><i>November 1897.</i></span></p> + +<p><span class="pagenum" id="Page_7">[Pg 7]</span></p> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CONTENTS">CONTENTS.</h2> +</div> + +<table class='toc'><tbody> + +<tr> +<td class="tdl">CHAP.</td> +<td></td> +<td class="tdr">PAGE</td> +</tr> + +<tr><td colspan="3"></td></tr> + +<tr> +<td></td> +<td class="tdl">LIST OF ILLUSTRATIONS.</td> +<td class="tdr"><a href="#Page_8">8</a></td> +</tr> + +<tr> +<td class="tdr">I.</td> +<td class="tdl">OCEANOGRAPHY</td> +<td class="tdr"><a href="#Page_9">9</a></td> +</tr> + +<tr> +<td class="tdr">II.</td> +<td class="tdl">SHALLOW-WATER FAUNA</td> +<td class="tdr"><a href="#Page_23">23</a></td> +</tr> + +<tr> +<td class="tdr">III.</td> +<td class="tdl">SHALLOW-WATER FAUNA OF THE TROPICS</td> +<td class="tdr"><a href="#Page_55">55</a></td> +</tr> + +<tr> +<td class="tdr">IV.</td> +<td class="tdl">SURFACE-SWIMMING FAUNA (INVERTEBRATES)</td> +<td class="tdr"><a href="#Page_82">82</a></td> +</tr> + +<tr> +<td class="tdr">V.</td> +<td class="tdl">SURFACE-SWIMMING FAUNA (VERTEBRATES)</td> +<td class="tdr"><a href="#Page_118">118</a></td> +</tr> + +<tr> +<td class="tdr">VI.</td> +<td class="tdl">DEEP-SEA FAUNA</td> +<td class="tdr"><a href="#Page_135">135</a></td> +</tr> + +<tr> +<td class="tdr">VII.</td> +<td class="tdl">COMMENSALISM AND PARASITISM</td> +<td class="tdr"><a href="#Page_146">146</a></td> +</tr> + +<tr> +<td class="tdr">VIII.</td> +<td class="tdl">THE ORIGIN OF THE MARINE FAUNA</td> +<td class="tdr"><a href="#Page_172">172</a></td> +</tr> + +<tr> +<td></td> +<td class="tdl">INDEX</td> +<td class="tdr"><a href="#Page_180">180</a></td> +</tr> + +<tr> +<td></td> +<td class="tdl">ADVERTISEMENTS</td> +<td class="tdr"><a href="#Page_184">184</a></td> +</tr> +</tbody></table> + +<p><span class="pagenum" id="Page_8">[Pg 8]</span></p> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="LIST_OF_ILLUSTRATIONS">LIST OF ILLUSTRATIONS</h2> +</div> + +<table><tbody> + +<tr> +<td class="tdl">ILLUSTRATION</td> +<td class="tdr">PAGE</td> +</tr> + +<tr> +<td class="tdl"><i><a href='#frontispiece'>Frontispiece.</a></i>—A Jelly-fish with the fry of the Horse Mackerel (from specimens captured by Mr F.W. Gamble off Valentia).</td> +<td class="tdr"><a href="#Page_2">2</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig1'>Fig. 1</a>—Globigerina Shell</td> +<td class="tdr"><a href="#Page_21">21</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig2'>Fig. 2</a>—Radiolarian Shells</td> +<td class="tdr"><a href="#Page_22">22</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig3'>Fig. 3</a>—Common Pipe-fish (from Royal Natural History)</td> +<td class="tdr"><a href="#Page_25">25</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig4'>Fig. 4</a>—Phyllopteryx (from Royal Natural History)</td> +<td class="tdr"><a href="#Page_26">26</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig5'>Fig. 5</a>—Diagrams of Eyes</td> +<td class="tdr"><a href="#Page_27">27</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig6'>Fig. 6</a>—A branch of the Zoophyte Obelia</td> +<td class="tdr"><a href="#Page_30">30</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig7'>Fig. 7</a>—Medusa produced +by Obelia</td> +<td class="tdr"><a href="#Page_31">31</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig8'>Fig. 8</a>—A Bivalve Mollusc</td> +<td class="tdr"><a href="#Page_35">35</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig9'>Fig. 9</a>—The common Sole</td> +<td class="tdr"><a href="#Page_37">37</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig10'>Fig. 10</a>—The Angler (from Royal Natural History)</td> +<td class="tdr"><a href="#Page_38">38</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig11'>Fig. 11</a>—Vertical section of a Balanus (after Claus)</td> +<td class="tdr"><a href="#Page_40">40</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig12'>Fig. 12</a>—Nauplius larva of a Balanus (after Groom)</td> +<td class="tdr"><a href="#Page_41">41</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig13'>Fig. 13</a>—Sea-urchin</td> +<td class="tdr"><a href="#Page_43">43</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig14'>Fig. 14</a>—Smooth-shelled +Gastropod</td> +<td class="tdr"><a href="#Page_47">47</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig15'>Fig. 15</a>—Spiny Gastropod</td> +<td class="tdr"><a href="#Page_47">47</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig16'>Fig. 16</a>—A Cuttle-fish</td> +<td class="tdr"><a href="#Page_49">49</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig17'>Fig. 17</a>—The Wrasse</td> +<td class="tdr"><a href="#Page_51">51</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig18'>Fig. 18</a>—The John Dory</td> +<td class="tdr"><a href="#Page_54">54</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig19'>Fig. 19</a>—Polyp of a Madrepore Coral (after Fowler)</td> +<td class="tdr"><a href="#Page_58">58</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig20'>Fig. 20</a>—Chætodon</td> +<td class="tdr"><a href="#Page_62">62</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig21'>Fig. 21</a>—Globe-fish</td> +<td class="tdr"><a href="#Page_64">64</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig22'>Fig. 22</a>—Stereosoma</td> +<td class="tdr"><a href="#Page_67">67</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig23'>Fig. 23</a>—Coral-reefs</td> +<td class="tdr"><a href="#Page_69">69</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig24'>Fig. 24</a>—Periophthalmus</td> +<td class="tdr"><a href="#Page_74">74</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig25'>Fig. 25</a>—Free-swimming +Copepod (after Claus)</td> +<td class="tdr"><a href="#Page_88">88</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig26'>Fig. 26</a>—Swim-bladder of +Velella</td> +<td class="tdr"><a href="#Page_96">96</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig27'>Fig. 27</a>—Solitary form of +Salp</td> +<td class="tdr"><a href="#Page_99">99</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig28'>Fig. 28</a>—Pteropod</td> +<td class="tdr"><a href="#Page_101">101</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig29'>Fig. 29</a>—Shells of Foraminifers</td> +<td class="tdr"><a href="#Page_104">104</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig30'>Fig. 30</a>—Globigerina</td> +<td class="tdr"><a href="#Page_105">105</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig31'>Fig. 31</a>—Young larva of a Star-fish</td> +<td class="tdr"><a href="#Page_111">111</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig32'>Fig. 32</a>—Pluteus larva</td> +<td class="tdr"><a href="#Page_113">113</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig33'>Fig. 33</a>—Long-spined Barnacle-nauplius (after Chun)</td> +<td class="tdr"><a href="#Page_116">116</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig34'>Fig. 34</a>—Sun-fish</td> +<td class="tdr"><a href="#Page_122">122</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig35'>Fig. 35</a>—The common Porpoise</td> +<td class="tdr"><a href="#Page_129">129</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig36'>Fig. 36</a>—A deep-sea Fish (after Filhol)</td> +<td class="tdr"><a href="#Page_139">139</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig37'>Fig. 37</a>—Hermit-crab and Sponge</td> +<td class="tdr"><a href="#Page_149">149</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig38'>Fig. 38</a>—Section through a Sponge showing Hermit-crab</td> +<td class="tdr"><a href="#Page_150">150</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig39'>Fig. 39</a>—A Trepang</td> +<td class="tdr"><a href="#Page_153">153</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig40'>Fig. 40</a>—A Crab-gall</td> +<td class="tdr"><a href="#Page_158">158</a></td> +</tr> + +<tr> +<td class="tdl"><a href='#fig41'>Fig. 41</a>—A parasitic Copepod</td> +<td class="tdr"><a href="#Page_169">169</a></td> +</tr> +</tbody></table> + +<p><span class="pagenum" id="Page_9">[Pg 9]</span></p> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="THE_STORY_OF_LIFE_IN_THE_SEAS">THE STORY OF LIFE IN THE SEAS.</h2> +</div> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_I">CHAPTER I. +<br><span class="medium">OCEANOGRAPHY.</span></h2> +</div> + +<p>One of the most important facts that has been +established by modern investigations of the Sea +is that there is no region in its vast extent that +is entirely devoid of animal life. The surface +waters in the Equatorial calms and the ice-cold +waters between the ice-bergs of the Arctic +regions are densely populated by animals, large +and small; the heavy and heated waters of the +Mediterranean and Red Seas, and the cold and +comparatively fresh waters of the Norwegian +fjords, the shallow waters of the coasts and the +greatest depths of the ocean-beds all present us +with their characteristic forms of living creatures. +There is no Azoic region known to us. Wherever +we use the trawl or dredge we may expect to +find some representatives of the various classes +of marine animals. But the seas exhibit so many +varying conditions that, as we might have expected, +the animals that characterise one region +are absent from another; and while, in some +places animal life is abundant, in others it is +very scarce; just as on land we find the grass-lands +<span class="pagenum" id="Page_10">[Pg 10]</span> +and forests teeming with life, and the +great deserts and mountain tops inhabited only +by a few solitary Lizards, Birds or Insects.</p> + +<p>In order that we may fully understand, then, +the nature of the problems concerning the distribution +of animals through the seas, it is of +importance to consider first the conditions under +which they must live in the different parts of +the ocean. A knowledge of geography is clearly +necessary for those who study the distribution of +terrestrial and aërial animals, and equally necessary +is it for those who wish to learn something +about the distribution of the aquatic animals, to +consider first of all the rudimentary principles of +hydrography. The principal Sea areas of our +globe may be roughly divided into two groups: +namely, the great oceans—the Atlantic, Pacific +and Indian Oceans—and the Inland seas, which +are partly enclosed by land, such as the German +Ocean, the Mediterranean Sea, and the Red Sea. +Taking the areas of the great oceans and the seas +together, we find that no less than 141 millions +of square miles, or nearly three-quarters of the +surface of the globe, are covered with water. +Moreover, these great areas are continuous, so +that it would be possible for an animal, other +conditions being favourable, to pass from any +one sea, such as the Black Sea, to any other, +such as the Hudson’s Bay, without leaving the +water,—an important fact in the consideration of +the distribution of marine forms of life.</p> + +<p>The depth of the sea varies very considerably +in the different parts of the world. In the inland +seas the water is comparatively shallow, but in +<span class="pagenum" id="Page_11">[Pg 11]</span> +the great oceans it is very deep. In the middle +of the North Sea, for example, we should not +expect to find a depth much exceeding 250 +fathoms, but in the Atlantic or Pacific Oceans +we have to pay out more than 2000 fathoms of +the sounding-line before the bottom is reached. +In some parts of the ocean-basins a few very +deep holes or furrows may be found in which +the depth exceeds 4000 fathoms, or 24,000 feet. +One of these deep holes occurs in the Atlantic +Ocean, a little to the North of the Virgin Islands +in the West Indies, and there is another in the +Pacific Ocean close to the coast of Japan; but +the greatest depth that has yet been found is +one recently discovered by H.M.S. “Penguin” off +the coast of New Zealand of over 5000 fathoms. +Apart, however, from the fact that these very +great depths are only of local occurrence, the +areas of deep water—that is, of more than 2000 +fathoms—are so much greater than the areas of +shallow water, that when we make a calculation +of the average depth of the sea we find it is no +less than 2100 fathoms, or 12,600 feet.</p> + +<p>The temperature of the sea is another feature +which undoubtedly influences very greatly the +character of its Fauna. The main source of the +heat of the sea is the sun—for the heat derived +from submarine volcanoes must be comparatively +so small that we may omit it from consideration. +Consequently we find that in the Equatorial +regions the surface waters of the ocean are +warmer than they are in the Temperate regions. +These, again, are warmer than in the Arctic +circles. But water is well-known to be a bad +<span class="pagenum" id="Page_12">[Pg 12]</span> +conductor of heat, and therefore the direct influence +of the sun affects only the most superficial +layers. In the Equatorial region of the Pacific +Ocean, for example, the surface temperature is +sometimes as high as 80° Fahr., at 100 fathoms +from the surface it is only 60°, at 400 fathoms +only 45°, and at 1000 fathoms only a few degrees +above freezing point. On the land the temperature +falls as we pass from the coast to the +high plateaux and mountains, and we find snow-capped +mountains in Central Africa just as in +Switzerland or Norway. In the sea the temperature +falls as the thermometer is sent deeper +from the surface. Just as on the land the snow +line of the mountains is reached at high altitudes +in the Tropics, at lower altitudes in the Temperate +regions, and in the Arctic circle at the +level of the sea, so in the sea the cold water that +is found 500 fathoms below the surface in the +Tropics, reaches a higher level in the Temperate +regions, and is at the surface in the Arctic +circle.</p> + +<p>There is however one important point of difference +between the distribution of these low +temperatures on the land and in the oceans, in +that they are broken in the former, and continuous +in the latter. If we were to imagine an aquatic +animal that could only live in temperatures +below 35° Fahr., it would be able to travel +below the surface from one pole to the other, or +from one ocean to another; but it would be +impossible for a terrestrial animal, exhibiting +the same peculiarity, to leave the Arctic circle +or the Alpine region without traversing lands +<span class="pagenum" id="Page_13">[Pg 13]</span> +where the temperature is higher than that which +is necessary for its existence. It might be supposed +from what has just been said that the +temperature of the water at the bottom is constant +for the same number of fathoms of depth. +This is not, however, the case. The temperature +of the sea-bottom of the great ocean-beds is +approximately the same, varying from 28° F. +in the Atlantic to 35° F. in the Pacific; but in +places where main basins occur, surrounded on +all sides by shallower ridges, the temperature +of the bottom of the basin is the same as that of +the lowest ridge. For instance, the temperature +of the bottom of the Sulu Sea, lying between +Borneo and the Philippines, is 40° F. at a depth +of over 2000 fathoms. Again, the temperature +of the Red Sea is as high as 70° F., although +depths of 1200 fathoms occur in its central +portions; and this is the same as the temperature +at the Straits of Babel Mandeb, which are +200 fathoms deep, and form the only outlet to +the open ocean. These facts probably cause +considerable modification in the character of the +animals inhabiting such enclosed basins, but +further investigations are needed before we can +arrive at any very definite conclusions in the +matter.</p> + +<p>Another important element that must be taken +into consideration in studying the environment +of marine animals, is the quantity and character +of the salts held in solution by the sea-water. In +the first place we must remember that the sea-water +normally contains a far greater percentage +of salts in solution than the water of rivers and +<span class="pagenum" id="Page_14">[Pg 14]</span> +lakes, and this causes it to be very much heavier. +If a tumbler be half filled with sea-water, upon +which some fresh water is slowly and carefully +poured, there will be for some time very +little mixture of the two fluids, the heavier +sea-water remaining at the bottom, and the +lighter fresh water at the surface. Now the +density of the sea-water, or in other words the +amount of salts in solution, is not the same over +the whole world, and the differences that may +be observed in this respect are due, in most +cases, to the simple physical principle just +enunciated. If we could imagine a river pouring +its waters into a perfectly calm, tideless sea, we +should be able to trace the fresh river water far +away from the coast, for it would simply float on +the heavier sea-water without mixing with it to +any appreciable extent. In most cases, however, +the tidal-waves, rushing up and down the river +estuaries, stir up the fresh and salt water together, +and cause a very considerable mixture, +so that the water becomes either distinctly salt +or brackish. Where very large quantities of +fresh water are poured into the ocean, as, for +example, at the mouth of the Amazon or the +Mississippi, the surface water remains so fresh +that the salt taste can hardly be appreciated at +a distance of some miles from the coast. This +fact sufficiently indicates the influence of great +rivers upon the density or saltness of the sea-water +in their neighbourhood, and the reader +will be prepared for the statement that many +inland seas, such as the Black Sea, are appreciably +less salt than the great oceans. +<span class="pagenum" id="Page_15">[Pg 15]</span></p> + +<p>Again, the ocean water itself is not of the same +density in all latitudes. In regions where there +is a copious rainfall and the sea is not frequently +disturbed by severe storms, the rain takes some +time to mix with the heavier salt water on which +it falls, and consequently there may always be +discovered in these localities a thin stratum of +comparatively fresh water on the surface of the +ocean. In some inland seas where there is considerable +evaporation and a slight rainfall, as for +example, the Red Sea and the Mediterranean, the +sea-water reaches an even higher degree of concentration +than it does in the open ocean. The +following table will serve to illustrate these +facts:—</p> + +<ul> +<li>Density of rain-water, 1·00.</li> +<li>Density of the Black Sea surface, below 1·025.</li> +<li>Density of the Atlantic Ocean surface (west of the Canaries), 1·0275.</li> +<li>Density of the Mediterranean Sea, over 1·028.</li> +<li>Density of the Red Sea, 1·030.</li> +<li>Density of the bottom water of the Atlantic, 1·029 (west of the Canaries).</li> +</ul> + +<p class="sa1">That the rate of movement of the water influences +very largely the character of the animals +that live in it, is a fact that it is not necessary to +discuss fully in this place; but as it is undoubtedly +one of the factors which must be taken into consideration +in discussing the character and possible +origin of the Fauna of any particular region, +a brief survey must be given of some of the +principal causes of the movements of the water +and the characters of the tides and currents which +are manifest in the sea. Twice every twenty-four +<span class="pagenum" id="Page_16">[Pg 16]</span> +hours the water of the sea rises and falls. +This movement is due to the attracting influences +of the sun and moon, and is, as is well-known, +greater when the moon is full and when it is new +than at the intermediate times. If the distribution +of land and water on the surface of our globe +were different, and a free waterway occurred +round the world, right in the Equatorial band we +should probably find a double tidal-wave rushing +round the earth every twenty-four hours. +As it is, however, the great tidal-wave is checked +by the continents, and as it approaches the coasts +is retarded and diminished in force. In Archipelagoes +and along broken coast lines the tidal-waves +produce true surface currents, which frequently +run with great rapidity and exert considerable +corroding action upon the rocks. In +many estuaries and bays the tide rushes in with +such force that the water is heaped up to a great +height against the land. At the entrance to the +Bay of Fundy, for example, the rise at spring-tides +is no less than 70 feet, and at the Cardiff +docks the difference of level between high and +low spring-tides is 42 feet. The tumultuous ebb +and flow of such masses of water along the coast +is fatal to some forms of animal life and favourable +to others, and so to some extent it modifies +the character of the Fauna.</p> + +<p>In addition to the surface currents of the +coast, produced by the tidal-waves, there are +also the true ocean-currents, which must be +briefly considered. They are caused by the +winds which blow constantly in a definite direction +across the oceans. The prevailing winds +<span class="pagenum" id="Page_17">[Pg 17]</span> +not only raise the sea into waves, but drive the +superficial layers of the water over the subjacent +layers in one direction. In studying a map of +the great ocean-currents, we notice a well-marked +one lying to the North of the Equator in both +the Atlantic and Pacific. This flows from East +to West and follows very closely the lines of the +prevailing winds in that region. Similarly in +the temperate regions of the Southern Hemisphere +there is an ocean-current, flowing however +in this case in the opposite direction—from West +to East—and so corresponding with the trade-winds +of that part of the world. The well-known +Gulf-stream of the North Atlantic, although +modified in some respects by other more complicated +causes, also follows for part of its course +the general direction of the prevailing winds.</p> + +<p>The currents just described are surface currents +only, and do not affect to any great extent the +mass of the subjacent waters in the ocean-basins. +It is difficult to estimate the depth to which their +influence reaches, but it is not probable that it +extends more than 200 fathoms below the surface. +In addition to these, there is also a series of slow +currents in the deep waters flowing in definite +directions. In the Tropical regions the waters +are constantly being heated by the sun, and +passed away by the trade-winds to the North +and South and ultimately towards the poles. +In their long and complicated journey they are +gradually cooled down until, in the regions of +the ice-bergs, they reach a temperature just +above the freezing point of sea-water. Here the +water, being colder and therefore heavier than +<span class="pagenum" id="Page_18">[Pg 18]</span> +that of the other regions of the world, sinks to +the bottom, and gradually returns in a deep-seated +mass towards the Equator, where, welling +up from the bottom, it replaces the heated layers +of the surface. It is almost impossible to determine +with accuracy the rapidity and exact +direction of these deep-sea-currents. It is extremely +probable that they are immensely +modified by the irregularities of the bottom and +the outline of the coast banks, but their exact +topography must remain for the present one of +the secrets of the abyss that are not revealed to +us. All that can be said is, that the warm +surface water which passes from the Tropics +towards the North and South is replaced by +deep-seated Polar currents, which account for +the extremely cold water that is found at great +depths in the ocean-basins, and also for some of +the peculiarities of the marine Fauna, which will +be referred to later on.</p> + +<p>The character of the sea-bottom in various +parts of the world must be referred to before +passing on, for there can be little doubt of the +important effect it has upon the Fauna. In the +neighbourhood of continents the bottom of the +sea varies very considerably. The great rivers +bring with them in suspension the products of +the wear and tear of mountains and valleys; the +coast line, washed by the continuous ebb and flow +of the tides, contributes some of its substance to +the formation of the sea-bottom; and the countless +millions of animals and plants of the shallow +waters leave their skeletons and shells as they +die to form an integral part of the floor of the +ocean. <span class="pagenum" id="Page_19">[Pg 19]</span> +Thus the sea-bottom in the neighbourhood +of the land is formed partly by terrigenous +deposits, varying of course in character with the +geological nature of the land itself, and partly +by the animal and vegetable deposits of the +coast. In some cases the deposits brought by +the rivers can be traced in the sea-bottom for +a very great distance from the coast. The +characteristic mud of the Congo river can be +traced 600 miles from its mouth, and it is said +that the Arabian Sea and the Bay of Bengal are +carpeted for 1000 miles by the mud brought +down by the Ganges and the Indus. Leaving +out of consideration, however, for the moment +the exceptional cases of such large rivers as these, +we may say that the influence of the land +deposits upon the character of the sea-bottom +extends to a distance seawards of about 250 +miles. If we had a complete and careful survey +of all the coast lines, it would be possible for +us to draw a line round the great continents +marking the limit of the deposits of river and +coast mud. This line has been called the mud-line +by Mr John Murray, and, as he has clearly +pointed out, it is characterised by an abundant +and extremely interesting Fauna.</p> + +<p>The sea-bottom, then, within the limits of the +mud-line, is very largely composed of deposits +from the land brought down by the rivers. In +some volcanic regions of the world this is, to a +great extent, augmented by lava and water-logged +pumice, and in other districts by the mud and +stones dropped by the melting ice-bergs. The +influence of animals and plants upon the formation +<span class="pagenum" id="Page_20">[Pg 20]</span> +of the sea-bottom is often very great indeed +in shallow water, though it varies considerably +in different parts of the world. In the neighbourhood +of the British coast, for example, the sea-bottom +is, in many places, carpeted with the +calcareous Sea-weed, <i>Lithothamnion</i>,—in other +places the dredge will come up crammed full of +bivalve shells. But such instances as these in +which the floor of the sea is covered with animal +or vegetable shells, are comparatively rare and of +small extent in the neighbourhood of land in the +Temperate regions, and in nearly all localities the +true terrigenous deposits can be readily obtained +by the use of a small meshed dredge. In the +warmer regions of the world, however, the sea-bottom +in the shallow water is over great areas +completely covered by animal and vegetable +products. In the West Indies, and in some +parts of the Eastern coasts of Tropical America, +in the Eastern Archipelago and the coast of +East Africa and its islands, Coral-reefs are found. +These are entirely built up of the skeletons and +shells of animals, and a few Coralline Algæ. In +the vicinity of these reefs the floor of the sea +is for miles carpeted with the broken-down +skeletons of these animals, sometimes in the +form of a fine coralline sand, sometimes of large +lumps studded with knolls of living Corals, +Molluscs, Sea-urchins, and other creatures. We +find, therefore, in the warmer regions of the +world immense areas of shallow water in which +the terrigenous deposits take but a very small +part in the formation of the sea-bottom, animal +and vegetable life being so vigorous and active +<span class="pagenum" id="Page_21">[Pg 21]</span> +as to be able to form enough shells and skeletons +to cover every available part of its surface.</p> + +<figure class="figcenter illowp79" id="fig1" style="max-width: 11.3125em;"> +<img alt="" class="w100" src="images/fig1.jpg" id="img_images_fig1.jpg"> +<figcaption> +<span class="smcap">Fig. 1</span><br> +<span class="small">Globigerina Shell from a deep-sea ooze.</span> +</figcaption> +</figure> + +<p>Far away from continental lands, and at great +depths, the character of the sea-bottom completely +changes. At a distance of 100 miles +from the coasts of America or Europe, for example, +the land deposits have already found +their resting-place, and the animal life in the +depths of the Atlantic is poor in skeleton-forming +genera. However, the surface waters +of the ocean teem with creatures of all sorts +which, as they die, drop down +their skeletons and shells in a +gentle shower to form a fine deposit on the bottom. +When we get beyond the mud-line, +then, and use the dredging or +sounding apparatus in depths +of 1500 to 2500 fathoms, we +find that the bottom is largely +composed of the shells of such +surface animals as the Pteropods +and Globigerinas, and according to the +relative abundance of these forms it is called +Pteropod Ooze or Globigerina Ooze. In still +greater depths than these the character of the +bottom again changes, and we find a deposit +which is commonly known as the Red clay. The +explanation of this change of character depends +upon the fact that sea-water exercises a slightly +solvent action upon carbonate of lime, and the +shells of the Globigerinas and other forms are, in +seas of a depth of over 2500 fathoms, dissolved +before they can reach the bottom. The only +<span class="pagenum" id="Page_22">[Pg 22]</span> +shells that can survive this long journey are the +siliceous shells of the Diatoms and Radiolarians, +and in those parts of the ocean where these +organisms live in abundance their empty shells +form an important percentage of the composition +of the Red clay. Over a very considerable area +of the Pacific Ocean, however, the Red clay contains +only a minute proportion of these shells, +and its composition has given rise to a good deal +of discussion among the authorities. It may be +considered to be a conglomerate of the horny +fragments of dead surface-living animals, of +volcanic and meteoric dust, and of small pieces +of water-logged pumice-stone.</p> + +<figure class="figcenter illowp91" id="fig2" style="max-width: 23.8125em;"> +<img alt="" class="w100" src="images/fig2.jpg" id="img_images_fig2.jpg"> +<figcaption> +<span class="smcap">Fig. 2</span><br> +<span class="small">Radiolarian Shells from a deep-sea deposit.</span> +</figcaption> +</figure> + +<p>In some of the very deep holes of the Pacific +<span class="pagenum" id="Page_23">[Pg 23]</span> +Ocean the mud is almost entirely composed of +Radiolarian shells, and is then called “Radiolarian +ooze”: and in the Southern Sea a mud +called Diatom ooze has been found, which consists +principally of the siliceous shells of these +minute algæ. Notwithstanding these varieties +of the mud, and others that space does not allow +me to refer to at length, we may suppose that +if the floor of any one of the great oceans were +exposed it would have the appearance to a +traveller of a vast desert-like expanse, without +a stone, a rock, or a cliff to vary the monotony +of the scene. At one time it was supposed to +be an absolute plain, without any important +change of level from the mud-line of one continental +coast to the other; but the result of +modern submarine explorations has been to prove +that in all the great ocean-basins, hills and ridges, +as well as troughs and deep holes occur, which +break the monotony of the generally smooth and +level character of the bottom.</p> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_II">CHAPTER II. +<br><span class="medium">SHALLOW WATER FAUNA.</span></h2> +</div> + +<p>Having considered thus briefly the general conditions +under which the animals of the sea must +live, we may now consider more in detail the +special conditions of shallow water life.</p> + +<p>In water of only a few fathoms in depth, the +direct light of the sun is capable of reaching and +influencing all living things that occur, either at +<span class="pagenum" id="Page_24">[Pg 24]</span> +the bottom, at the surface, or in the intermediate +waters. Great as the influence of direct sunlight +must be upon animals, it is even greater upon +plants. Nearly all the Sea-weeds are, like the +plants of the dry land, dependent upon carbonic +acid gas dissolved in the water for one of the +most important constituents of their food, but it +can only be absorbed by the plant in the presence +of sunlight. It is possible, therefore, for Sea-weeds +to flourish in the shallow waters of the sea, +while they are necessarily absent from the deeper +and darker regions to which the rays of the +sun cannot penetrate. Everyone knows that in +the shallow waters of our own coast there is in +many places a dense tangle of Wracks and long, +flat ribbon-like Sea-weeds growing on the bottom, +and that on and amongst these weeds a rich +harvest of animals awaits the eager shore collector. +It is true that there are vast fields of +sand on which the Sea-weeds are few and far +between, but we may say that wherever they +can obtain a secure foothold in the shallow waters +of the British coast there they will grow and +multiply in great profusion. We must not, however, +jump too hastily to the conclusion that the +same is true for all parts of the world. The +British coasts are particularly rich in Sea-weeds, +in fact a distinguished botanist once said that +they probably present us with the greatest +number of genera and species of any coast line +of the same extent in the world. In the Temperate +regions of both the Southern and Northern +Hemispheres there is generally a rich Sea-weed +flora, but in the warmer regions it is less luxuriant, +<span class="pagenum" id="Page_25">[Pg 25]</span> +and on the Coral-reefs of the Tropical +seas it is remarkably poor.</p> + +<p>Turning our attention for the present to the +Temperate regions, let us consider the influence +that the Sea-weeds have upon the animals of the +shallow waters. In the first place we find that +they afford shelter and +support for a large number +of animals which could +hardly live without them. In +the roots of the weeds may be +found little Crabs and Molluscs, +which occur nowhere else; and +clinging to the long waving +branches are many forms of Sea-anemones, +Zoophytes, flattened +limpet-like Molluscs, Ascidians, +and other forms of animal +life. The great forests of +weeds are also the haunts +of many queer Fish, +Prawns, Crabs, and Sea-slugs, +which hunt their prey or +hide from their enemies amidst +the shelter of the stems and +branches.</p> + +<figure class="figcenter illowp80" id="fig3" style="max-width: 24.8125em;"> +<img alt="" class="w100" src="images/fig3.jpg" id="img_images_fig3.jpg"> +<figcaption> +<span class="smcap">Fig. 3</span><br> +<span class="small">The common Pipe-fish.</span> +</figcaption> +</figure> + +<p>Now many of these animals, +which together make up the +Fauna of the Sea-weed region, have assumed, +in the course of the ages of evolution, not +only the colours of the Algæ on which they +live, but in some cases even forms which render +them at first sight more like plants than animals. +The slender Pipe-fish, for example, which is not +<span class="pagenum" id="Page_26">[Pg 26]</span> +uncommonly found amongst the bright green +Sea-weeds of our coast, is wonderfully similar, +both in form and colour, to the weeds on which +it lives. The Sea-horses, which have such a +curious form out of the water, in their natural +surrounding resemble the weeds so closely that +they may be easily overlooked. A still more +remarkable example is to be found in the +curious fish Phyllopteryx, in which the body +is provided with long branched processes, making +it we may suppose much more difficult +to distinguish in its natural haunts than even +the Pipe-fish or Sea-horse.</p> + +<figure class="figcenter illowp75" id="fig4" style="max-width: 19.625em;"> +<img alt="" class="w100" src="images/fig4.jpg" id="img_images_fig4.jpg"> +<figcaption> +<span class="smcap">Fig. 4</span><br> +<span class="small">Phyllopteryx.</span> +</figcaption> +</figure> + +<p><span class="pagenum" id="Page_27">[Pg 27]</span></p> + +<p>Many other examples to illustrate this feature +of the Sea-weed Fauna could be quoted, but +sufficient has been said at present if we have +indicated to the reader the manner in which, by +the indirect influence of light, the form and +colour of animals may be modified for their life +among the marine plants. The presence of light, +however, modifies directly the character of the +animals themselves in many respects.</p> + +<figure class="figcenter illowp100" id="fig5" style="max-width: 110.9375em;"> +<img alt="" class="w100" src="images/fig5.jpg" id="img_images_fig5.jpg"> +<figcaption><span class="smcap">Fig. 5</span><br> +<span class="small">Diagrams of Eyes of <i>A</i> Whelk, <i>B</i> Lobster, +<i>C</i> Scallop, <i>D</i> Fish.</span> +</figcaption> +</figure> + +<p>The statement that many of the animals of +the shallow water are provided with eyes because +there is light is, when carefully examined, found +to be strictly true, however anomalous it may +seem to be. There must have been light in the +shallow waters of the sea when the first primordial +forms of life made their appearance, and +it was this light which, step by step, led to the +evolution of the most complicated and perfect +forms of eye from the simplest pigment spot of +the Protozoan to the eye of the Lobster and the +Fish. We may say that all animals that freely +swim in the shallow waters or that crawl and +creep on the rocks and sands at the bottom are +provided with eyes. The Fish are provided with +a pair of eyes which present us with the same +<span class="pagenum" id="Page_28">[Pg 28]</span> +general features that we find in the other Vertebrates. +Lobsters, Crabs and Prawns have each +a pair of stalked eyes, which are probably as +perfect in their functions as the Vertebrate +eye, although built up on an entirely different +model. Whelks, Winkles, and other Gastropods, +although so slow in their movements, have each, +upon or close to their tentacles, a pair of minute +eyes, which are much simpler and probably far +less perfect in form than the eyes of their more +highly organised neighbours. Even the little +Jelly-fish, Star-fish, Sea-urchins, and other creeping +forms of life, are provided with specialised +pigment spots, which we have good reason to +believe enable them to perceive the rays of +light.</p> + +<p>But we must notice that it is only the animals +that are capable of locomotion from place to +place that need these organs of vision, and that +the stationary forms are blind. In the large +class of the Lamellibranchs, for example, to which +the Oyster and the Mussel belong, we find that +with a few exceptions there are no eyes. These +animals, after the first few stages of their life +are past, settle down into the sand, or fasten on +to a rock and remain there until their life is +done. Their food, consisting of the minutest +specks of animal and vegetable life, is brought +to them by the sea-currents; they do not need +nor desire to seek the society of their relations, +and when their enemies approach they resign +themselves almost without an effort to the inevitable. +To such animals eyes would be useless, +and so nature has withheld them.</p> +<p><span class="pagenum" id="Page_29">[Pg 29]</span></p> +<p>There are, however, a few Lamellibranchs +that possess good eyes, eyes that are almost +as complicated in their structure as the Vertebrate +eye; and not a single pair only, but sixty, +eighty, a hundred, or even more, may be found +on a single individual. Such a Lamellibranch is +the common Scallop which may be seen in many +of our fishmongers’ shops. Unlike most of the +group, this animal is able to make long flights +through the water by the flapping together of its +shells, and there can be no doubt that on the +approach of danger it uses this method of locomotion +for escape. One of its most deadly +enemies is the Star-fish, which forces the shells +apart and sucks out the flesh by means of its +protrusible stomach. When a Star-fish is placed +in an aquarium in which there are some Scallops, +lying, as they do, on their sides, with the valves +slightly open, showing the double row of gleaming +metallic eyes on the margin of the mantle, +the Star-fish immediately moves, with what in +such an animal may be considered extraordinary +rapidity, straight in the direction of the Scallop. +Before, however, it reaches its prey, the coveted +victim gives four or five vigorous flaps of its +shells and swims away to another part of the +tank. This suggests that the eyes of the Scallop +are used in the light as a means of giving warning +of the approach of an enemy, and they are +found in the Scallops only, among common +British bivalves, because they alone possess +this power of swimming away. Of course if +there were no light in the water the eyes would +be useless, and it is an interesting fact that the +<span class="pagenum" id="Page_30">[Pg 30]</span> +Scallops which live in the darkness of the great +depths of the ocean are quite blind.</p> + +<figure class="figcenter illowp41" id="fig6" style="max-width: 9.8125em;"> +<img alt="" class="w100" src="images/fig6.jpg" id="img_images_fig6.jpg"> +<figcaption> +<span class="smcap">Fig. 6</span><br> +<span class="small">A branch of the Zoophyte Obelia.</span> +</figcaption> +</figure> + +<p>Very interesting examples of the connection +between the presence of eyes and the power of +locomotion are found among the sedentary or +fixed forms of life. The great class of Sea-squirts +or Tunicates includes a number of genera, most +of which are, in the adult +condition, immoveably +fixed to the bottom, and +in that stage have no +eyes; but the eggs which +they produce give rise to +little creatures, like tad-poles +in form, which swim +about freely in the water. +Each of these tad-poles +has a large eye in its +brain, which remains so +long as the animal leads +a free life. As soon, however, +as it settles down +upon the rock which is +to become its permanent +resting-place through life, +the eye and the organ of +locomotion, the tail, both +degenerate and ultimately disappear. Again, +we often find upon rocks, Sea-weed, old shells, +and the like, some curious delicate branching +organisms called Zoophytes. Notwithstanding +their general resemblance in form to Sea-weeds, +these Zoophytes are known to be animals. +Each tuft or branch is formed by a number of +<span class="pagenum" id="Page_31">[Pg 31]</span> +delicate little Polyps, each with a crown of +tentacles round a terminal mouth. The Polyp +cannot move away from the branch it grows +upon, nor the branch from the stem, nor the +stem from the rock on which it rests, and none +of these minute creatures are provided with +eyes. There are, however, a few Zoophytes that +give rise to buds, which grow into the form of +minute Jelly-fish (or Medusæ, as they are called); +and these, becoming detached from the parents, +swim away and lead an independent existence. +These Medusæ are in many cases provided with +simple little eyes. During +their short life they are +drifted away by the sea-currents +to some distance +from their parents, and produce +a number of eggs which +are capable of developing +into a new fixed colony of +Polyps.</p> + +<figure class="figcenter illowp100" id="fig7" style="max-width: 22.6875em;"> +<img alt="" class="w100" src="images/fig7.jpg" id="img_images_fig7.jpg"> +<figcaption> +<span class="smcap">Fig. 7</span><br> +<span class="small">Medusa produced by Obelia.</span> +</figcaption> +</figure> + +<p>We may consider it one of the maxims of +Science that in a population of animals which +possess eyes, colour as well as form is of extreme +importance. As well as the alteration in form +that takes place in the animals living among +Sea-weeds, we find a modification in colour in the +creatures dwelling among rocks or on the sand, +so that they may resemble the ground on which +they live. No more striking example of this +could be found than in the common Shrimps of +our coasts. Anyone who has watched them in +the sea-pools must have been struck with their +close resemblance to the sand. In fact it is only +<span class="pagenum" id="Page_32">[Pg 32]</span> +by close observation that they can be distinguished +from it. In an aquarium, too, it may +be observed how very much the upper sides of +Soles, Flounders, Turbots and other flat fishes +are like the sand in colour, while the under sides +are almost invariably pure white. The black +colour of the Lobsters, speckled and striped with +blue, has a close resemblance to the holes and +crannies of the rocks among which they live. +The bright transparent green Prawns are almost +invisible as they move about among the Sea-weeds, +and Sea-slugs assume all manner of beautiful +colours according to the ground on which they +feed.</p> + +<p>On the Coral-reefs of the warmer regions of +the world the pools that are left when the tide +goes down are characterised by their brilliancy +of colour. The bright purple, green, and yellow +tips of the Coral branches, the red and bright +green Sponges, and the white pieces of dead and +broken Corals make up a scene of beauty which +can only be compared with a bed of variegated +flowers. Here the Fish, Prawns, and other moving +animals have assumed the most gorgeous colours +in patterns of spots and stripes which verily +astonish the naturalist when he sees them for +the first time. The great Sea-perches, with their +sides covered with bright red or brown blotches, +the curious Trigger-fish, with bright red, blue, or +yellow bands crossing their bodies, the banded +Lobsters, and the spotted Cuttlefishes, strange +and conspicuous as they may seem when they +are taken out of the water, are in life but in +harmony with their surroundings, and, in reality, +<span class="pagenum" id="Page_33">[Pg 33]</span> +less conspicuous than they would be if less +brilliantly arrayed.</p> + +<p>I remember on one occasion as I was watching +some expanded Polyps in a little shore pool in +the Tropics, I noticed something suddenly move +close to the coral block on which I was standing. +As there was no escape from the little pool, nor +any holes in which the creature could hide +itself from my observation, I searched with +diligence to find it again, but for a long time +without avail. Suddenly it moved again, and +then I saw, resting on the brilliantly coloured +corals, a remarkable little Shrimp called by +zoologists <i>Stenopus</i>. Its body, which was almost +transparent, was marked by a number of +bands of a bright red colour, it had enormously +long antennæ similarly banded, and its legs and +body were covered with short red-tipped spines. +When I succeeded in safely landing it in my +collecting bottle I felt perfectly astonished that I +had been so baffled by such a lovely little jewel, +so bright, so strange, and so generally conspicuous +did it then seem to be.</p> + +<p>The colours of the animals I have referred to +hitherto may be accounted for by their need to +escape the attention of their enemies, or to avoid +detection in the pursuit of their prey; but the +animal colour problem is not yet exhausted. +The beautiful colours of the Anemones, Corals, +Sponges and many other sedentary forms of +animal life, and the marvellous patterns on the +shells of Molluscs cannot be due to these causes. +Many ingenious theories have been brought forward +to explain away the difficulty, but none of +<span class="pagenum" id="Page_34">[Pg 34]</span> +them seem to be perfectly satisfactory, and consequently +it is unnecessary to enunciate them in +detail in this small book.</p> + +<p>The character of the bottom of shallow water, +especially in the neighbourhood of the coasts, +presents us with so many variations that it would +be a long task to consider in detail all the different +adaptations that the animals exhibit. The +Fauna of the sand, shingle, and mud at the +mouths of rivers, of the rocks of iron-bound +coasts, and of the coral-reefs, each present us with +many curious kinds of modification of form and +structure. A brief reference to one or two +characteristic regions must be made before passing +on.</p> + +<p>The sandy bottoms which are so prevalent, +not only upon our coasts, but in nearly all +parts of the world, invariably support a Fauna +with many curiously altered forms. In walking +across the sands at low water we may have often +noticed many worm-like and twisted columns of +sand; these are the casts of the common Lug-worm, +which is a favourite bait for many kinds +of Fish. The Lug-worm lives in a U-shaped +tube, which it forms from a slimy secretion of the +body; it feeds by swallowing the sand in which +it burrows, extracting from it as it passes through +the intestine whatever animal or vegetable food it +may contain. There can be little doubt that the +sand is a very poor form of diet, and that an +immense quantity must pass through the body +of the animal compared with its weight in order +to afford sufficient nourishment. It has been +reckoned that as many as 82,433 casts may be +<span class="pagenum" id="Page_35">[Pg 35]</span> +found on an acre of sand where conditions are +favourable for these Worms, and that they would +weigh together nearly 2000 tons. This would +mean that the whole mass of the sand would +pass through the bodies of Lug-worms on an +average of once in every twenty-two months.</p> + +<p>But the Lug-worm is only one of +the many forms of life that burrow +in the sand. A very large number +of bivalve Molluscs live with the +greater part of their bodies perpetually +buried. Their organisation +is such that their food and the water +that is used for respiration can be +brought to them by a tubular prolongation +of the body called the +siphon. Some of these animals live +much deeper down than others, and +while some have but feeble powers +of moving either up or down in their +burrows, others can penetrate to +great depths with extraordinary +rapidity.</p> + +<figure class="figcenter illowp26" id="fig8" style="max-width: 11.5em;"> +<img alt="" class="w100" src="images/fig8.jpg" id="img_images_fig8.jpg"> +<figcaption> +<span class="smcap">Fig. 8</span><br> +<span class="small">A Bivalve Mollusc, showing below the +foot with which it burrows into the sand, and above the +siphons.</span> +</figcaption> +</figure> + +<p>The shell of a Lamellibranch, +called the Razor-shell (<i>Solen</i>), is not +an uncommon object of the sea-shore +where stretches of sand occur. When +the animal is alive it has the power of +burrowing down so quickly that it is practically +impossible for one man to capture a specimen by +digging, when it is thoroughly alarmed. Occasionally, +however, the sea itself, when lashed into fury +by a storm, is a better digger than the Solen is a +burrower; and after a heavy storm in the Isle +<span class="pagenum" id="Page_36">[Pg 36]</span> +of Man I have seen the shore littered with Solens +scooped out of the sand by the force of the +waves and cast up with lacerated shells to fall +an easy prey to the Seagulls.</p> + +<p>The sandy bottoms in shallow waters are also +the haunts of many kinds of Fish that are specially +modified in form and colour to resemble +their surroundings. The large family of the +Skates have their bodies compressed from above +downwards so that they can lie perfectly flat +upon the sand. Their upper surface is deeply +pigmented, giving them a general resemblance +to the ground on which they lie; but to assist +them in escaping observation they have a habit +of shaking their fins in such a manner as to +scatter a considerable quantity of sand over their +bodies. Thus it can well be understood that in +the dim light of the sea-bottom the little Fish +and Shrimps, which form a large portion of their +food, may approach quite close to them without +being in the least aware of the danger into which +they are running. The upper side of the Skate +is also armed with a number of sharp and hard +spines, and in some forms—called the Sting-rays—one +of these, situated at the base of the tail, +is much larger than the others, and provided +with muscles so that it can be suddenly erected. +In connection with this spine there is a poison-gland +and duct. The wound that is inflicted +upon the arms or feet of the fishermen by this +formidable weapon of offence is said to be of a +very serious nature.</p> + +<p>Some of the Skates, too, show another very +interesting modification of structure, which, however, +<span class="pagenum" id="Page_37">[Pg 37]</span> +is not directly associated with their mode +of life, but may be briefly referred to here +whilst dealing with the family. This is the +electric organ. In the younger stages of the +common English Skate a small region of the +muscular system on each side of the base of the +tail becomes changed into an electric organ, but +the discharges which it is able to give are so +feeble that they can only be appreciated by a +galvanometer. In the Torpedo, however, the +electric organs are very large indeed, and situated +one on each side of the head. They can give a +shock which is powerful enough to kill small +animals and to stun larger ones. With such a +formidable weapon of offence and defence, it is +clear that the need for active movements is +considerably diminished, and the Torpedoes are +described as being exceedingly slow in progression +and incapable of the violent movements +of other Skates.</p> + +<figure class="figcenter illowp100" id="fig9" style="max-width: 14.8125em;"> +<img alt="" class="w100" src="images/fig9.jpg" id="img_images_fig9.jpg"> +<figcaption> +<span class="smcap">Fig. 9</span><br> +<span class="small">The Common Sole, showing both eyes +on one side of the head.</span> +</figcaption> +</figure> + +<p>The other Flat Fishes found on sandy bottoms +belong to a different group altogether, and are +characterised by their bony skeletons and other +features. The +Soles and their +allies do not, +like the Skates, +lie flat upon +their bellies, +but are <i>laterally</i> +compressed +and lie upon one side. The side which is +habitually uppermost is of the colour of the +sand, and the other almost invariably pure white. +<span class="pagenum" id="Page_38">[Pg 38]</span> +In the course of their development the Soles +undergo very extraordinary changes in form to +reach the perfectly flattened condition of the +adult stage. These changes affect many of the +organs of the body, but perhaps the most interesting +of all is the history of the eyes. In +the young Soles, which swim almost vertically, +like the majority of fishes, there is one eye o +each side of the head, but as they grow older +and gradually take to the habit of swimming on +one side, the eye of that side sinks down into +the head, and rotating as it goes passes through +to the other side. This process naturally leads +to a considerable distortion of the skull, so that +the bones of the adult Sole show as complete a +<span class="pagenum" id="Page_39">[Pg 39]</span> +want of symmetry as can be found in any Vertebrate.</p> + +<figure class="figcenter illowp97" id="fig10" style="max-width: 23.5625em;"> +<img alt="" class="w100" src="images/fig10.jpg" id="img_images_fig10.jpg"> +<figcaption> +<span class="smcap">Fig. 10</span><br> +<span class="small">The Angler.</span> +</figcaption> +</figure> + +<p>Some of the Bony Fish, however, that live on +the sand are flattened dorso-ventrally like the +Skates. The Angler or Fishing-frog, for example, +is a Flat Fish, which is perfectly symmetrical. Like +the other Flat Fish its upper surface is coloured +in such a manner as to resemble the ground on +which it lives. Its great mouth, armed with +formidable rows of sharp-pointed teeth, is directed +upwards, and it receives its name from a curious +tentacle terminating in a brightly-coloured knob +which dangles over its mouth. +The brightly-coloured knob looks no doubt a tempting morsel +to the little Fish upon which the Angler preys, +but the greed or curiosity, whichever it may be, +that induces them to inspect the bait leads them +to the fate which follows one snap of the great +tooth-armed jaws.</p> + +<p>The Fauna of the shallow waters where rocks +abound also possesses many peculiarities. In the +first place we must remember that the rocks, +being firm and hard, present a basis upon which +many of the sedentary forms of life that would +be swept away or smothered if they attempted +to live on the ever-shifting sands, can fix themselves. +Consequently the rocky bottom is characterised +by a rich Fauna of those groups of +animals, which, in the adult condition, are immoveably +fixed. If a large stone or a water-logged +piece of timber that has been at a depth +of a few fathoms for some months or years be +captured in the dredge and brought on board +for examination, it is sure to present the observer +<span class="pagenum" id="Page_40">[Pg 40]</span> +with a multitude of firmly-fixed creatures. +Among them there is almost certain to be found +a number of small conical shells, made up of a +series of triangular plates, fixed to the rock by +their bases. These are commonly spoken of as +Barnacles (<i>Balanus</i>), and they pass through an +interesting history. For many years they were +considered, from the character of their shells, +to be allied to the Molluscs, but an examination +of the soft parts of the +animal shows that, +unlike any Molluscs, +they are provided with +six pairs of jointed +legs; and a still further +study of their anatomy +proves beyond a doubt +that they can no longer +be classified, with any +pretence of scientific +accuracy, with that +group.</p> + +<figure class="figcenter illowp78" id="fig11" style="max-width: 12.1875em;"> +<img alt="" class="w100" src="images/fig11.jpg" id="img_images_fig11.jpg"> +<figcaption> +<span class="smcap">Fig. 11</span><br> +<span class="small">Vertical section of a Balanus, showing animal <i>in situ</i> in its shell.</span> +</figcaption> +</figure> + +<p>The secret of their +true relationship was not discovered until the +story of the development was worked out, when +it was found that the eggs they discharged each +gave rise to a little larva called Nauplius, which is +provided with three pairs of legs like the larvæ of +some of the Prawns and their allies. The result +of these observations then was to prove that the +Barnacles are really Crustaceans, notwithstanding +the fact that, unlike most of that group, they +are, in the adult stage, permanently fixed to the +rocks. +<span class="pagenum" id="Page_41">[Pg 41]</span></p> + +<p>On the same piece of stone there will most +probably be found several twisted or coiled tubes +of lime, formed by a little Sea-worm called +Serpula. When living in the water the head of +this worm projects from its shell and expands +a circlet of delicate tentacles, by means of which +the food is brought to the mouth. One of these +tentacles is specially modified and enlarged at +the extremity to form a conical knob, which, +when the animal is retracted into the shell, closes +the aperture like a stopper.</p> + +<figure class="figcenter illowp91" id="fig12" style="max-width: 18.9375em;"> +<img alt="" class="w100" src="images/fig12.jpg" id="img_images_fig12.jpg"> +<figcaption> +<span class="smcap">Fig. 12</span><br> +<span class="small">Nauplius larva of a Balanus, enormously magnified.</span> +</figcaption> +</figure> + +<p>Then there may be found some spherical or +lobate masses of a fleshy consistency, white, pale +pink or yellow in colour, and studded with +numerous star-shaped apertures. When these +are allowed to remain in a basin of fresh sea-water +for some time, each one of the star-like +apertures opens, and a beautiful transparent little +<span class="pagenum" id="Page_42">[Pg 42]</span> +Polyp with eight-feathered tentacles gradually +unfolds itself, only to be slowly withdrawn into +the mass when the vessel is shaken or otherwise +disturbed. These Polyps form colonies, known +as <i>Alcyonium digitatum</i>.</p> + +<p>Now it is to be noticed that none of these +three examples of the sedentary Fauna can move +in the least degree from the rock or shell to +which they are fixed. When once the young +larva has taken up its position there it must +remain until old age or some disaster brings its +life to an end. When they are first hatched +from the egg that is thrust into the water by the +parent, they pass through a larval stage that, like +the Nauplius of the Barnacle, is active and free. +Then they are carried away from the parent +stock partly by their own active movements, but +more particularly by the tides and currents of +the sea-water. At last a change in their structure +occurs. They sink to the bottom, become attached +to a rock or stone, complete their metamorphosis, +and remain anchored to the spot for +the rest of their lives.</p> + +<p>The number of different forms of animal life +which constitutes this sedentary Fauna of rocky +coasts is very great indeed. In addition to the +Barnacles, Worms and Alcyoniums, there are +numerous species of Sea-anemones, Sponges, +Corals, Zoophytes, Sea-squirts, and other forms, +and in <i>all</i> these cases the eggs give rise to +free-swimming larvæ, by which the distribution of the +species is effected.</p> + +<p>Another group of animals, which forms an +important feature of some rocky coasts, are the +<span class="pagenum" id="Page_43">[Pg 43]</span> +Boring-molluscs. The Rock-borers belong to +many different species. Some of them, such as +the Pholases, make long cylindrical holes in +chalk, and even in harder rocks. The Teredo +is the borer, commonly known as the Ship-worm, +on account of its powers of penetrating +into timber. The long calcareous tube which +it forms as it works its way into the wood, +gives it a superficial resemblance to a large +sedentary worm, but it is in reality a bivalve +Mollusc, specially modified in structure for its +peculiar habits.</p> + +<figure class="figcenter illowp98" id="fig13" style="max-width: 22.0625em;"> +<img alt="" class="w100" src="images/fig13.jpg" id="img_images_fig13.jpg"> +<figcaption> +<span class="smcap">Fig. 13</span><br> +<span class="small">Sea-urchin with large thick spines.</span> +</figcaption> +</figure> + +<p>The next group of animals we have to consider +in the Fauna of the rocks includes all those that +slowly creep or crawl, without possessing any +powers of rapid locomotion. Amongst these +may be mentioned the Sea-urchins and Star-fishes. +<span class="pagenum" id="Page_44">[Pg 44]</span> +The former possess spherical or heart-shaped +bodies covered with a formidable array of +spines, among which there protrude several rows +of soft transparent tubes terminating in little +cup-like discs. Some of these tubes—or tube-feet +as they are called—are fixed to a rock, and +the heavy body is slowly dragged after them; +another set is then attached, whilst the former +is released to obtain another hold a little further +on. The progress is slow, but the Urchin is able +to climb the smooth face of an absolutely perpendicular +rock with perfect ease or to get over +any other obstacles that may be in its path. The +Star-fishes are similarly provided with tube-feet, +but in their case these are confined to the lower +surface of the body, the upper side being entirely +devoid of them. Star-fishes have a very wide +distribution in the sea, and occur on sandy shores +as well as among rocks and shingles. If a specimen +be watched gliding slowly and smoothly +over the sea-bottom and then the mouth be +examined with a pocket lens, a doubt might +arise in the mind of the young naturalist as to +the justice of the charge that is made against +these animals of their being the principal enemies +of the hard-shelled Oysters. But the charge is +well founded, for if a Star-fish be placed in an +aquarium with an Oyster or a Cockle, or, in fact, +almost any bivalve Mollusc, it may be seen to +clasp its prey in its arms and slowly but firmly +and surely force open the shells, and then protrude +on to the soft parts a long tubular stomach +which gradually digests and absorbs them. The +Star-fishes, then, are undoubtedly to be reckoned +<span class="pagenum" id="Page_45">[Pg 45]</span> +among the most voracious and destructive inhabitants +of the shallow waters, and it is probable +that the covering of spines which we find so +commonly among shallow water animals is an +adaptation to prevent or render difficult the +operations of these creatures.</p> + +<p>The Gastropod Molluscs form another large and +important group of creeping animals of rocky +coasts. On nearly all our own coasts numerous +Periwinkles may be seen clinging to the rocks at +low tides, and if a search be made in the deeper +pools and on the rocks nearest to the low-water +marks many other species will be found of animals +with spirally-coiled shells which are included +in this group of Gastropods. The Periwinkles +on the rocks might at first sight be thought to +belong to the sedentary group of animals, but +when the water covers them again, or when they +are put into an aquarium, they may be seen to +protrude a head and an elongated slimy foot, +which, gliding over the surface of the rock, drags +the great shell and its contents with it. On the +approach of danger the foot and head are withdrawn +into the shell, and the animal rests secure +from many enemies that might otherwise have +found it a dainty morsel. Some of the Gastropods +are purely vegetable-feeders, but most of +those living in shallow sea-water feed upon +Molluscs and other animals. It might well be +a matter for wonderment when the soft head and +little mouth of a Gastropod, such as a Whelk, +are examined, that it is carnivorous and attacks +and devours animals as large as itself. But the +anatomist shows us that hidden in the recesses +<span class="pagenum" id="Page_46">[Pg 46]</span> +of that mouth there is a ribbon beset with +numerous sharp little teeth, which by a complicated +mechanism can be worked backwards and +forwards in such a manner that it can bore a hole +through very thick and dense shells; and, the soft +parts being reached, a tube is protruded which +dissolves and sucks them up into the animal’s +stomach.</p> + +<p>Many people must have noticed that numbers +of the bivalve shells that are cast up on the sand +at low tide are perforated close to the hinge by a +neat little round hole. This is the hole made by +some predaceous Gastropod which, having killed +its prey and devoured all that is digestible of it, +leaves its empty shells at the mercy of the waves. +Amongst the rocks numerous species of Gastropods +are found, some undoubtedly carnivorous, +others herbivorous. The many beautiful forms +and colours that their shells assume may be seen +in any good museum or conchological cabinet. +Some of them are very minute, others are provided +with a shell more than a foot in length; +some are marked with numerous coloured spots, +others with bands or lines; some have perfectly +smooth shells, others are ribbed or spiny. It +is extremely difficult to account for all these +modifications, partly because it is impossible to +study the animals alive in their natural habitats +a few fathoms below the surface of the sea, and +partly because life in the shallow waters must be +so complicated that we are at a loss to understand +the value to a species of slight modifications in +structure such as these. The difficulty that has +been found in explaining these various forms and +<span class="pagenum" id="Page_47">[Pg 47]</span> +colours has led some naturalists to the belief that +they are of no importance to the species in the +struggle for existence, that they are, as it were, +the accidental result of some process of excretion, +and not the outcome of a long series of slight +changes, bringing about at length an adaptation +of form most suitable to the habits of the animal. +Such views are, however, to be accepted with +great caution, and most zoologists will be contented +to wait until our knowledge is much +greater than it is at present, before wholly agreeing +with them.</p> + +<div class="row"> + <div class="column1"> +<figure class="figcenter illowp35" id="fig14" style="width: 80%"> +<img alt="" class="w100" src="images/fig14.jpg" id="img_images_fig14.jpg"> +<figcaption> +<span class="smcap">Fig. 14</span><br> +<span class="small">Smooth-shelled Gastropod.</span> +</figcaption> +</figure> +</div> + <div class="column2"> +<figure class="figcenter illowp35" id="fig15" style="width: 80%"> +<img alt="" class="w100" src="images/fig15.jpg" id="img_images_fig15.jpg"> +<figcaption> +<span class="smcap">Fig. 15</span><br> +<span class="small">Spiny Gastropod.</span> +</figcaption> +</figure> + </div> +</div> + +<p class='cb'>Another great class of animals which has many +representative forms among the rocks is the group +of Crustaceans. The Lobster, the Prawn and the +Crab are all familiar examples of this class. +They may be found by searching rock pools at +low-water, or can be captured in basket-work +traps in places beyond low-water mark. When +undisturbed they crawl slowly over the rocks +and weeds by their long jointed legs, searching +for their prey, but when alarmed the Lobster +and the Prawn can, by violent flapping movements +of their tails, dart rapidly backwards +through the water, while the Crab beats a +hasty retreat sideways into some shelter among +the rocks. Like many of the Molluscs, the +Crustaceans have a hard covering or shell to +protect them from many of the dangers to which +soft-bodied animals would be exposed, but a +momentary glance at them would be sufficient to +satisfy the most inexperienced eye that there are +many and important differences in the character +of the shells of these two great groups of animals. +<span class="pagenum" id="Page_48">[Pg 48]</span> +One important distinction between them, however, +might well escape observation, and that is, +that whilst in the Mollusc the shell increases +gradually in size during the life of the animal, in +the Crustaceans it cannot do so. In the Lobsters +and Crabs the shell is periodically cast off entirely, +and for a day or two at each period the skin of +the animal is quite unprotected. A new shell is +gradually formed, and this is hardened and thickened +until it assumes a form similar to that of +the one that has been lost, but larger. During +the moult the Crustacean usually hides itself in +<span class="pagenum" id="Page_49">[Pg 49]</span> +a hole in the rocks and waits patiently until the +new shell has grown.</p> + +<figure class="figcenter illowp22" id="fig16" style="max-width: 12.125em;"> +<img alt="" class="w100" src="images/fig16.jpg" id="img_images_fig16.jpg"> +<figcaption> +<span class="smcap">Fig. 16</span><br> +<span class="small">A Cuttle-fish.</span> +</figcaption> +</figure> + +<p>The animals included under the popular names +of Cuttlefishes, Squids and Octopuses are also +capable of crawling about among the rocks by +their long feeler-like arms; but they are in the +habit, as well, of making prolonged +journeys through the water, by +pumping the sea-water through a +tubular siphon situated on the +under side of their bodies. These +animals possess in such a remarkable +degree the power of changing +colour that they might be called +the Chamæleons of the sea. As +they pass slowly through the water +from one part of the coast to another +the colour of the skin changes so as +to resemble the colour of the rocks +or weeds which are below them. +These changes are brought about +by numerous little bladders in the +skin which are filled with different +coloured fluids, and are worked by +a complicated system of muscles +under the control of special nerves +from the brain. When the colour +blue is predominant, it is found that all the +bladders containing blue fluids are dilated, the +others being constricted; when the colour is red +the red bladders only are dilated, and so on; +and as the nervous response to the colour of the +rocks perceived by the eye is practically instantaneous, +the change in the general colour of +<span class="pagenum" id="Page_50">[Pg 50]</span> +the body brought about by the dilatations of these +vesicles is extremely rapid. Many other animals +have the power of changing colour, but in no +group is the alteration more rapid and remarkable +than in this order of Cuttlefishes and Squids. +Another very interesting feature presented by +these animals is their ability to discharge suddenly +a cloud of inky substance into the water. +Their principal enemies are the Whales, Porpoises +and some of the larger Sharks and other +Fish. When these animals approach, or any +other danger is feared, the Cuttlefishes discharge +into the water from a special bag, called the ink-sac, +a quantity of black or brown pigment +which, diffusing rapidly, forms a cloud round +their bodies, in the obscurity of which they +frequently escape pursuit. The well-known +Sepia of painters is obtained from these ink-sacs.</p> + +<p>The last group of animals occurring among the +rocks are those capable of vigorous swimming +movements. Many Crustaceans, such as the +Lobsters and Prawns, are capable, as has just +been pointed out, of swimming rapidly through +the water by means of their powerful tails. But +this swimming power is only accessory to that of +crawling or creeping, and is used merely when +the animals are disturbed. Cuttlefishes and their +allies seem to spend a considerable portion of +their time in floating or swimming in the water, +but still they do crawl about among the rocks, +and very probably attack and feed upon their +prey entirely upon the sea-bottom.</p> + +<p>The members of the Rock-fauna which belong +<span class="pagenum" id="Page_51">[Pg 51]</span> +to the class of Fishes very rarely rest upon the +sea-bottom at all. They are not, as a rule, provided +with limbs which are capable of crawling +or creeping; and their mouths are adapted for +catching food that is swimming, or of browsing +upon or nibbling at fixed forms of life while their +bodies are still floating in the water. Nearly all +the animals living among the rocks that we have +hitherto spoken of, have some organs or some +specialised portion of the body-wall for resting +upon or for attaching themselves to the bottom.</p> + +<figure class="figcenter illowp100" id="fig17" style="max-width: 33.125em;"> +<img alt="" class="w100" src="images/fig17.jpg" id="img_images_fig17.jpg"> +<figcaption> +<span class="smcap">Fig. 17</span><br> +<span class="small">The Wrasse.</span> +</figcaption> +</figure> + +<p>The Anemones are attached by their bases; the +Sea-urchins and Star-fishes crawl by means of +their tube-feet; the Gastropod creeps over the +rocks by its broad flat foot, and the Octopus +stretches out its muscular arms and drags its +body along by the numerous suckers they bear. +In the Flat Fishes of the sandy and gravelly shores +we usually find a white under surface on which +they rest when waiting for their prey. Among +the Fish which frequent the rocks, however, +such as the Cods, the Whitings, and the Wrasse, +<span class="pagenum" id="Page_52">[Pg 52]</span> +there are no such surfaces. The body of the +Fish is usually more rounded in form, and no +well-marked limit can be assigned to the coloured +upper surface and the pale silvery under side. +These Fish are in nearly all cases rapid and +powerful swimmers, rushing through the water +after their prey, or away from their enemies, by +vigorous lateral movements of their tails.</p> + +<p>A curious exception to this general rule among +the Fish occurs in the family of the Lump-suckers. +These Fish are found on the English, +but more commonly on the Scottish coast, and are +distinguished by the presence of a sucker, formed +by the throat fins, on the under side of the head. +By means of this the Lump-sucker is able to +attach itself so firmly to rocks and stones that it +can only with considerable difficulty be removed +from the object to which it is attached.</p> + +<p>Of the Fish that are commonly found among +the rocks, a very considerable number migrate +from time to time to other parts of the sea, and +may be caught in the trawl on sandy or shingly +bottom, or even in the drift nets at the surface of +the sea. A large number of Fish belonging to the +family of the Codfishes frequent the rocks during +a part of their lives. The Pollack is distinguished +from most of the others by the absence of a barbel +on the lower jaw, and is one of the persistent rock +frequenters. In the adult condition it feeds almost +entirely upon other Fish, although in the younger +stages of its life Crustaceans, Worms, and other +Invertebrates seem to form the bulk of its food.</p> + +<p>The true Cod and the Haddock seem to have a +much wider range, occurring on shingly bottoms, +<span class="pagenum" id="Page_53">[Pg 53]</span> +where they are frequently caught in the fishermen’s +trawls, as well as in the neighbourhood of +rocks. The Hake feeds principally upon Pilchard, +Herrings and Sprats near the surface of +the sea.</p> + +<p>It is an interesting fact that the Fish belonging +to this one family have very different methods of +feeding. The Cod and the Pollack both hunt +their prey principally by day-light. The Pollack +is guided by its sight alone, the Cod-fish is assisted +by its barbel, which acts as a delicate feeler or +organ of touch. The Hake, on the other hand, retires +into deep water during the day-time, and only +comes to the surface at night to feed. Similarly +the Rockling hides away in holes or under stones +during the day-time, and only comes out to hunt +for the Crustaceans and little Fish upon which it +feeds at night.</p> + +<p>The development of these Fish presents some +features of interest, as showing us the changes +which occur in habit during their life-history. +The eggs of the Cod are buoyant, rising to the +surface of the sea as soon as they are spawned. +In twelve or fourteen days, according to the +temperature of the water, the larvæ are hatched +and swim about in large numbers just below the +surface, feeding upon minute Crustaceans and +other animals. A little later the young Cod +frequently shelter themselves under large Jelly-fishes, +feeding upon the numerous parasites +which infest those creatures. When they are +about a year old they are found feeding among +the sea-weeds on rocky coasts, and they migrate +into deeper water when they reach their full size. +<span class="pagenum" id="Page_54">[Pg 54]</span></p> + +<figure class="figcenter illowp100" id="fig18" style="max-width: 27.5625em;"> +<img alt="" class="w100" src="images/fig18.jpg" id="img_images_fig18.jpg"> +<figcaption> +<span class="smcap">Fig. 18</span><br> +<span class="small">The John Dory.</span> +</figcaption> +</figure> + +<p>The John Dory is a remarkable Fish, by no +means confined to the rocks, as its food often +consists largely of Pilchards and Herrings. It +differs from most of the Fish of similar habits in +being remarkably flattened from side to side. +This feature seems to be of service to it in the +peculiar manner it has of securing its prey. Mr +Cunningham, to whom we are indebted for this +interesting observation, says:—“It does not +overtake (its prey) by superior speed like the +mackerel, nor lie in wait for it like the angler, +but stalks it and approaches it by stealth. It is +able to do this in consequence of the extreme +thinness of its body, and the peculiar movement +of its hinder dorsal and ventral fins. The dory +places itself end on towards the fish it desires to +devour, and in this position it is evident that it +excites no alarm on the part of its prey. The +appearance of the dory seen in this way is a +mere line in the water, to which no particular significance +<span class="pagenum" id="Page_55">[Pg 55]</span> +can be attached. I have not particularly +noticed the effect of the ribbons of membrane, +which project from the dorsal fin. But I have +observed that the movements of the dory are very +gradual except in turning; it alters the position +of its body by a turn of the tail or side fins, and +then slowly swims forward by vibrating the +second dorsal and ventral, a movement which +causes very slight disturbance of the water. The +whole appearance of the dory in these actions is +suggestive of suppressed excitement, his eyes +being fixed on his prey.”</p> + +<hr class="tb"> + +<p>We have now considered some of the chief +features of animal life in the shallow seas, the +illustrations being taken principally from the +regions of our home shores. The shallow +waters of the tropics present us with so many +phenomena of striking interest and importance, +that the subject would be most incompletely +treated if they were left out of consideration +altogether, and, therefore, our next chapter will +be devoted to them.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_III">CHAPTER III. +<br><span class="medium">SHALLOW WATER FAUNA OF THE TROPICS.</span></h2> +</div> + +<p>The shallow waters of the Tropical seas present +us with so many different conditions of tides, of +coast lines, of temperature, of liability to storms, +and of other natural phenomena, that we find an +infinite variety in the general character of their +<span class="pagenum" id="Page_56">[Pg 56]</span> +Fauna. Just as on land, we find in one part of +the Tropics a dense forest, and in another a dry +desert, so in the Tropical seas we find on one +coast a crowded population of animals and plants, +and on another a sandy bottom, which is, comparatively +speaking, lifeless. In order to bring +before the reader some of the principal characters +of animal life in the shallow waters of the Tropics +it will be well to confine his attention to one +part of the world which is fairly well-known—namely, +the Malay Archipelago—and refer only +in passing to other localities. The most characteristic +feature of Tropical coasts is the Coral-reef, +and nowhere in the world may it be seen in more +exquisite variety than in the archipelagoes of the +East. Although, however, these vast structures +are so abundant on some coasts, others seem +to be entirely without them. They are not +found at all on the Western coasts of America or +of Africa, and even in some regions of the larger +islands in the Pacific and the Indian Oceans, +many miles of coast line may be devoid of them. +These curious and interesting variations in the +distribution of the reefs can be explained, but +the explanation will be more easily understood +when their general features have been described.</p> + +<p>It is a well-known fact that the great masses +of limestone which compose the reefs are formed +by the activity of countless thousands of minute +animals, but the popular idea of the general +form of these animals has been very much misled +by the unfortunate term “Coral insect,” which +has crept into many books of travel, and the +leading articles in the newspapers. The word +<span class="pagenum" id="Page_57">[Pg 57]</span> +“insect” is used by zoologists as a general term +for certain air-breathing animals that are widely +distributed over the surface of the earth. Many +of them are extremely tiny, and hence the +natural mistake has arisen in the untrained +mind that all minute animals are insects. It +might clear the ground a little if the reader +would note at once that “insects” are very +rarely indeed marine in habit. If there is a +need for a popular word for the animals that +form coral, it should be Coral “polyps” or Coral +“anemones.” The word “coral” has, from the +zoologist’s point of view, a very indefinite meaning, +for it is applied to the hard skeleton of +carbonate of lime formed by certain Sea-weeds, +Sponges, and Worms, as well as to that of +Coral-anemones and other Polyps. In many +places on the British coasts the sea-bottom is +very largely composed of a branching Coral +formed by a true Sea-weed called <i>Lithothamnion</i>, +and in other places very large lumps of rock are +made by a Worm named <i>Filograna</i>. In the +Tropical regions, too, the well-known Nullipores, +which in many places play an important part in +the formation of Coral-reefs, are of vegetable, +and not animal origin.</p> + +<p>However, the greatest part of the Coral-reef +is made by animals closely related to the Sea-anemones, +living together in colonies; and of all +the different kinds of Coral-polyps, by far the +most prolific as a reef-builder is one which will +be referred to in these pages as the Madrepore.</p> + +<figure class="figcenter illowp77" id="fig19" style="max-width: 22.1875em;"> +<img alt="" class="w100" src="images/fig19.jpg" id="img_images_fig19.jpg"> +<figcaption> +<span class="smcap">Fig. 19</span><br> +<span class="small">Polyp of a Madrepore Coral, showing the canals by +which it is connected with its fellows.</span> +</figcaption> +</figure> + +<p>Let us consider now the manner in which the +Polyps form the Coral. In a very old work on +<span class="pagenum" id="Page_58">[Pg 58]</span> +the natural history of Corals a statement is made +to the effect, that the Polyps construct the Coral +in much the same way as Bees build their hive, +or a Bird its nest. This very erroneous view +coincides closely with ideas which might easily +be gained by a casual observation of corals in a +museum. The lime is not, however, collected as +such from the sea by the Coral-polyps and +plastered round their bodies to form a house +or shelter, but it +is formed as a +secretion by the +activity of certain +organs of the +animal’s body, and +is consequently a +true shell or skeleton. +In a Coral, +which is formed +by a colony of +numerous Polyps, +the shell secreted +by each individual +fuses on to those +formed by its +neighbours, and +thus a communal shell is formed which may +assume a most complicated branching, bushy +form, according to the species of the Coral and +the conditions that are favourable or unfavourable +to the nourishment and growth of the +different parts of the colony. In such a Coral as +the Madrepore every individual Polyp is connected +with its neighbours by a system of +<span class="pagenum" id="Page_59">[Pg 59]</span> +branching canals; and as spaces are left for +these when the shell is formed, the dried Coral +is perforated by numerous tubular pores, and has +a soft, spongy texture which can be easily +crushed into a powder if trodden upon.</p> + +<p>In other Corals the canals of communication +between the Polyps are entirely at the surface, +and the shell that is formed is much harder and +imperforate. In others again colonies are not +formed, but each individual grows to a considerable +size and remains independent of its fellows +all its life.</p> + +<p>These, then, are three of the more important +varieties of Corals found on the reef, the Perforate, +the Imperforate, and the Solitary Corals; +but it must be remembered that all the Corals +of the reef cannot be included in these three +groups. The varieties are much more numerous +and in many cases much more complicated and +difficult to understand.</p> + +<p>Although the Coral-reefs of the Tropical world +have a general resemblance to one another, the +differences in detail are so great that it is impossible +to describe any one as typical. In sailing +over the edge of a reef near the coast on a calm +day, when the water is so clear that the bottom +can be seen at a depth of 8 or 9 feet, the reef +may, in some regions, be observed to change in +character every few minutes. In one spot there +may be clumps of living Corals surrounded by +beds of fine white sand; in another there will +be great stretches of branching Madrepores; in +another Madrepores, Mushroom-corals, the Imperforate +Brain-corals, Sponges, and many other +<span class="pagenum" id="Page_60">[Pg 60]</span> +forms of life will be clustered together; while +further on the predominant features will be the +soft and slimy Sarcophytums, looking like large +green toad-stools, some lumps of Organ-pipe +Corals and a few colonies of the Blue-coral.</p> + +<p>On other coasts I have wandered for miles along +a reef mainly composed of endless tangles of Madrepores, +with very little variation indeed in the +general form of the Corals, in the character of +the Sponges and Sea-weeds that grow with them, +in their colour or in any other detail. Anyone +reading the many accounts of Coral-reefs that +have been written by travellers, must be struck +with their inconsistency as regards many particulars; +and in no one point are they more inconsistent +than in the description of the colours—some +writing in glowing terms of the beauties of the +sea-gardens, and others complaining that their +charms have been grossly exaggerated. As a +matter of fact some reefs have a prevailing dull +green or brown tone, while others exhibit all the +colours of the rainbow in their more brilliant +shades and tints. Another cause of the discrepancy +is that some reefs can only rarely be approached +in a small boat owing to the breakers +that dash over them; whilst in the Tropical calms +a tiny canoe can with perfect safety be manœuvred +over the reefs during nine months of the year. +From my own experience I can assert that it +would be difficult indeed to exaggerate the glorious +beauty of some of the reefs in the Malay +Archipelago, more particularly of those where +many different kinds of Corals may be seen in +close proximity to one another. On such a reef, +<span class="pagenum" id="Page_61">[Pg 61]</span> +for example, there may be seen Madrepores with +bright violet growing-points to their branches, +orange or red Fan-corals, bright brick-red Sponges, +yellow Sarcophytums, emerald green Organ-pipe +Corals and dozens of other forms of animal life +in every imaginable colour. When seen from a +boat through two or three feet of water, these +portions of the reef look more like a beautifully +planted flower-bed than a mass of animals; but +the simile is not a complete one, for the branches +of the Madrepores, the great knobs and lumps of +the Brain and Organ-pipe corals, the fronds of +the Gorgonias and other forms make a wild mass +of organisms resembling a tangled thicket or a +miniature forest. At low-water of spring-tides +the living reef is partly left exposed, and then +the scene changes, for the Polyps retract their +tentacles after the manner of the Sea-anemones +and retreat as far as possible into the shelter +afforded by their shells.</p> + +<figure class="figcenter illowp100" id="fig20" style="max-width: 34.25em;"> +<img alt="" class="w100" src="images/fig20.jpg" id="img_images_fig20.jpg"> +<figcaption> +<span class="smcap">Fig. 20</span><br> +<span class="small">Chætodon.</span> +</figcaption> +</figure> + +<p>The interest of the living reefs is, however, by +no means confined to such organisms as the Corals +and Sponges, which are immoveably fixed to the +bottom; for numerous brightly-coloured Star-fishes, +Sea-urchins, Brittle-stars, Sea-slugs, and +their allies crawl about among the branches and +the débris of the dead Corals; while Crabs, Lobsters +and Shrimps of many kinds may be seen +swimming or crawling in search of their prey, +and the marvellously striped and spotted Coral +fishes dart hither and thither in the thicket, or +remain hovering in the water among the Corals. +The whole scene is most fascinating. As the boat +slowly drifts along, new and strange creatures are +<span class="pagenum" id="Page_62">[Pg 62]</span> +constantly coming into sight and disappearing +again. Here the writhing arms of a bright blue +Brittle-star may be seen embracing the stem of a +Coral-branch; there a curiously flattened Chætodon, +with its body marked by great diagonal +yellow bands, is nibbling at the young, tender +branchlets; in another place four or five Sea-urchins +with very long and slender spines are +lying apparently motionless on the bottom; while +a little further on a long black Slug-like creature, +the famous “Trepang” of commerce, is slowly +wending its way across the reef. Now and again +a large shoal of little Fish or a small party of +Cuttlefishes may be seen, and these may rapidly +be dispersed in all directions by the sudden dash +of a Sea-perch or a small Shark. The interest is +so varied, so many-sided, in these scenes of +animal life that the attention of the naturalist +<span class="pagenum" id="Page_63">[Pg 63]</span> +is with difficulty kept to any particular point. +The feature which is perhaps the most striking +is, however, the wonderful variety in the +colours of the animals and of the character +of their markings.</p> + +<p>If we consider the Fishes alone, we find +some of them have broad yellow bands running +diagonally across their bodies, others have thin +longitudinal stripes of blue and yellow, some +have a uniform bright red colour, and others +again have their red skins speckled with blue +spots. It would take more than a whole chapter +of this book to describe even the principal varieties +of pattern found on one such Coral-reef, but +the main fact that has to be related is that where +the reefs are built by brightly-coloured Polyps, +there we find these curiously marked Fishes. +There can be little doubt that the marking and +colouring does give a certain amount of protection +to them. Numerous individual cases have +been mentioned of Fishes which resemble some +particular Sea-weed or Coral; but this general +statement is the important one, that on a parti-coloured +background the striped and speckled +Fish are less conspicuous than those that are +modestly attired.</p> + +<p>The Fishes of the reefs, however, have other +means of protection than that afforded by their +colours. The Trigger-fish and Coffer-fish, for +instance, have a body encased in closely fitting +hard, thick scales, so that they might almost be +called “armour-plated fish”; and the Globe-fish +bristle all over with long and extremely sharp +spines. In the Trigger-fish there is a curious +<span class="pagenum" id="Page_64">[Pg 64]</span> +modification of the three front spines on the +back, to which their name is due. It is not +known precisely how they act, but they probably +form an effective weapon of defence. In the +same family of Fish we frequently find on each +side of the tail two or three rows of sharp spines, +which may also be regarded as defensive. In +the family of the Surgeons there is only one of +these spines on each side of the tail, and it is +much larger than any of those in the Trigger-fish, +and capable of being folded down into a +case in the skin like a clasp-knife. It is said +that these spines are connected with a poison-gland, +and can give very severe and painful +wounds, like the poison spines of our European +Sting-rays and Weavers.</p> + +<figure class="figcenter illowp99" id="fig21" style="max-width: 33.18em;"> +<img alt="" class="w100" src="images/fig21.jpg" id="img_images_fig21.jpg"> +<figcaption> +<span class="smcap">Fig. 21</span><br> +<span class="small">Globe-fish.</span> +</figcaption> +</figure> + +<p><span class="pagenum" id="Page_65">[Pg 65]</span></p> + +<p>A few days’ hunting on a Coral-reef will reveal +the fact that it supports a very considerable +population of Crustaceans. They are not at all +obvious at first to one who has had no previous +experience of reef-work, partly because they resemble +the general appearance of their surroundings +very closely, and partly because of their +habit of remaining perfectly motionless when +first alarmed. In form, many of them are, like +the Lobsters, Crabs and Prawns of our own +coasts, but their colours and markings are, like +those of the reef-fishes, characterised by their +brilliancy and their arrangement in bands and +stripes. The smaller ones can be caught after +a little practice with a simple hand-net, but the +larger ones are more easily captured by a rattan +noose in the pools, after the blocks of Coral are +loosened by a pick-axe and slowly turned over.</p> + +<p>The Coral-reef is a favourite hunting-ground +for the conchologist, some of the largest and +most beautiful shells in the world being found +amongst the Corals. In Celebes, the giant bivalves, +the huge Tridacnas, which are sometimes +two feet across, and whose shells have been +known to weigh as much as 500 lbs., may be +seen wedged in among the Corals. The mantle +of the living animal presents to the observer a +wonderful display of colour as it lies in the +shallow water with its shells open. The animal +is eaten by the Malays, who roast it on a tripod +spit over a fire, and cut it into steaks. A fair-sized +Tridacna will afford a good meal for four +or five men. The great Cowries, Helmet-shells, +and many other species may be found in hunting +<span class="pagenum" id="Page_66">[Pg 66]</span> +over the reefs, but their beauties are frequently +hidden, when alive, by the coal-black mantle +which folds back over the shell as they crawl +along. It must not be supposed, however, that +all the shells of the reefs reach to such enormous +size as those we have hitherto mentioned, for a +rich harvest of species awaits the eager conchologist +who hunts for the smallest shells he can find +in the pools. Within the last few years a large +number of new species of small Molluscs have +been described from the coral seas, many of which +do not attain to a total length of more than ⅛ +of an inch when perfectly adult, so that the +range in size of this class of animals is very great +indeed.</p> + +<p>So much has been said about the Madrepores, +the Imperforate Corals and the solitary Corals +of the reef, that the impression might be left that +all the Polyps of the Tropics differ from those of +the Temperate regions in the fact that they form +shells or skeletal structures. This is by no means +the case, for there are many species of true Sea-anemones +and other Polyps to be found on Coral-reefs +which make no shell at all, and others in +which the body-wall is strengthened by numerous, +but very minute spicules or grains of lime which, +on the decomposition of the animal’s body, fall +down into a shapeless powder or sand.</p> + +<p>True Sea-anemones are not very abundant on the +reefs of North Celebes, but many species have +been found on the Barrier-reef of the Australian +coast, and among them specimens reaching the +gigantic size of two feet in diameter—the largest +size attained by single individuals of the class of +<span class="pagenum" id="Page_67">[Pg 67]</span> +animals to which the Anemones belong. Another +family of Polyps called the Clavulariidæ belonging +to the Alcyonarians has some species which +make no skeleton of calcium carbonate. An illustration +of one of these is given below (<a href='#fig22'>Fig. 22</a>). +Another species, called <i>Clavularia viridis</i>, which +forms a few spicules in its body-wall, has a very +wide distribution in the East Indies. In some +places patches of it may be seen several square +yards in extent, and the crowds of little Polyp +heads with their eight-feathered tentacles waving +to and fro with the pulsations of the tide, is a +sight that excites immense interest and admiration +in the mind of the observer.</p> + +<figure class="figcenter illowp100" id="fig22" style="max-width: 33.3125em;"> +<img alt="" class="w100" src="images/fig22.jpg" id="img_images_fig22.jpg"> +<figcaption> +<span class="smcap">Fig. 22</span><br> +<span class="small">Stereosoma, one of the Clavulariidæ.</span> +</figcaption> +</figure> + +<p>One word more about the Corals. Where they +are so abundant in number and species, where +rocks hundreds of miles in extent are mainly +composed of their shells and skeletons, it might +<span class="pagenum" id="Page_68">[Pg 68]</span> +be thought that a rich profit could be gained by +collecting ship-loads of the Coral that is used for +making beads and brooches by our jewellers. +Any expedition, however, fitted out for this purpose +would end in disastrous failure, for the +Precious-coral is not known to occur anywhere +in the neighbourhood of Coral-reefs, but the +fishery is confined to certain parts of the Mediterranean +Sea. Species closely allied to the +Precious-coral, but of an inferior colour, have +been found in the Japanese waters. None of +the Coral structures found on the reefs have the +same delicate salmon-pink colour and probably +none of them are hard enough to take a good +polish.</p> + +<p>The Coral-reefs which occur in different parts +of the Tropical world were considered by Darwin +under three heads,—Barrier-reefs, Atolls, and +Fringing-reefs. The distinction between these +three kinds of reef is not one that can be insisted +upon scientifically, but the arrangement is convenient +for purposes of description.</p> + +<p>The Barrier-reefs (<a href='#fig23'>Fig. 23</a>, <i>B</i>) are situated at a +distance of one to eight miles from the coast, and +are separated from it by a lagoon of moderately +deep water. The Barrier-reef of New Caledonia +is said to be 400 miles in length and it follows +the general contour of the coast line.</p> + +<p>The Atolls (<a href='#fig23'>Fig. 23</a>, <i>C</i>) are ring-shaped islands +composed of coral limestone with a lagoon of salt +water within them, situated in the sea without +any definite relation to other existing land.</p> + +<p>The Fringing or shore-reefs (<a href='#fig23'>Fig. 23</a>, <i>A</i>) are +situated at a distance of 100 yards or less from +<span class="pagenum" id="Page_69">[Pg 69]</span> +the beach and separated from it by a shallow +lagoon which is frequently left as a dry sand-bank +at low tides.</p> + +<figure class="figcenter illowp100" id="fig23" style="max-width: 32.5625em;"> +<img alt="" class="w100" src="images/fig23.jpg" id="img_images_fig23.jpg"> +<figcaption> +<span class="smcap">Fig. 23</span><br> +<span class="small"><i>A</i>, Fringing-reef; <i>B</i>, Barrier-reef; <i>C</i>, Atoll. +<i>a</i>, sea; <i>b</i>, reef; <i>c</i>, rocks of the coast.</span> +</figcaption> +</figure> + +<p>Many forms of reefs are found in different parts +of the world, but they may all be looked upon +as special modifications of one of these three +groups. The facts which Darwin collected about +Coral-reefs in his memorable voyage round the +world in the <i>Beagle</i>, suggested to this great +observer that all the different forms of reef +must be related to one another, and he formulated +an ingenious theory to show how, by the +gradual sinking of the crust of the earth, +Fringing-reefs may have become, in the course +of a long period of time, either Atolls or Barrier-reefs. +Some doubts have recently been expressed +as to the truth of Darwin’s famous +“subsidence theory.” But, whether it is true +or not, to Darwin is due the credit of bringing +home forcibly to our minds the fact that Coral-reefs +are slowly undergoing changes of growth +and of destruction, which must lead to most +important and far-reaching alteration in the +character of the Tropical seas. It is not intended +<span class="pagenum" id="Page_70">[Pg 70]</span> +in this work to enter into a discussion +of the various alternative theories of Coral-reef +formation, but a few words may be added +on the method of formation of Coral limestone.</p> + +<p>In studying any one particular form of reef-building +Coral we can find a long series +of specimens from one inch in length up +to a certain maximum, which varies with the +species and the reef, but may reach over five +feet in diameter as can be seen in the specimens +now in the British Museum at South Kensington. +Beyond this maximum size—let us say four feet +in diameter—the Coral rarely grows, because at +a certain age, probably when the vitality of the +Coral is on the wane, the stalk of attachment +becomes so bored with parasitic Sponges, Worms, +Fungi and other organisms, that it is thoroughly +rotten. If a large block be picked up from the +reef, and with the help of two or three strong +natives carried ashore and broken up with a +hammer, a most interesting migration of Crabs, +Worms and other creatures occurs, and the +collecting bottles may be filled with a rich +variety of animals parasitic on the Coral. Now +the time comes when the stalk becomes so brittle +that a heavy wave breaks it in two, and the +Coral topples over and dies. If it falls into the +sand, either on the inside or the outside of the +reef and becomes buried, it may be preserved +fairly complete, but if it lodges between other +Corals the waves and the parasites between them +dissolve it and break it up into thousands of +pieces. This constant disintegration leads to +the formation of great quantities of coralline +<span class="pagenum" id="Page_71">[Pg 71]</span> +sand which fills up the interstices between the +living Corals, or gets washed over into the +lagoon, or falls as a talus over the seaward slope +of the reefs. In the latter case lumps of Coral +torn off from the reef become embedded in it and +form with it a bank which gives support to more +living Polyps on the seaward slope. Consequently, +in the course of many years, a reef +which was at one time only fifty yards from the +beach may have extended to a distance of a +hundred yards or more, growing, as it were, on +the skeletons or shells of the Corals that have +died. There can be little doubt that Coral-reefs +do grow seawards in this manner in some places, +but they may also be either beaten back or kept +for a long time perfectly stationary if the tides +are too strong or too slack.</p> + +<p>What the precise conditions are which favour +the growth seawards of Coral-reefs has not yet +been systematically investigated; but we may +suppose that if the tides are too strong the +sand has no opportunity of settling between the +Coral blocks and forming a solid limestone rock, +and if they are too slow the Coral-polyps do +not get sufficient nourishment to allow them +to build fast enough to counteract the solvent +action of the water.</p> + +<p>An interesting point connected with the Coral-reefs +is the manner in which they are formed at +first. A volcanic upheaval gives rise to a new +island which, in the course of time, is surrounded +by a Fringing-reef. How does this reef begin?</p> + +<p>The answer to this question has been recently +given by the observation of the formation of new +<span class="pagenum" id="Page_72">[Pg 72]</span> +Corals on the shores of the island of Krakatoa +which is situated in the Sunda straits, and was +the seat in 1884 of one of the most violent +volcanic eruptions of historical times. After the +eruption the sea-bottom round the island was +found to consist of a fine volcanic mud, in which +it may be believed no Coral embryos could find a +secure foothold. Now it is known that living +Corals give rise to a number of very minute +larvæ which for a period of time swim freely in +the water, eventually settling down on some solid +stone or shell to give rise by growth and budding +to the Coral blocks. These larvæ frequently +settle down on a piece of floating pumice-stone +and after a time grow to such a size that they +sink it. If, in sinking, they fall upon the bottom +in shallow water they form together a substratum +on which other larvæ can settle and +flourish. This is apparently the manner in +which Coral clumps are beginning on the slopes +of Krakatoa and these will undoubtedly give +rise in time to a more or less complete Fringing-reef.</p> + +<p>Any further discussion on this point would +lead us into subjects beyond the scope of this +book, but enough has been said to indicate to +the reader the manner in which the countless +Coral-polyps may, in the course of time, change +the position of the reefs on Coral shores, thereby +altering the set of the tides there, changing the +position of the sand-banks, affecting the rate of +erosion of the cliffs, and in other ways causing +important modifications of the coast line.</p> + +<p>I have mentioned that the ground on the +<span class="pagenum" id="Page_73">[Pg 73]</span> +growing edge of the Coral-reef is carpeted with +Corals, Sponges and many other forms of animal +life; in the water swim countless Fish, and the +branches of the Corals yield to the naturalist +innumerable forms of creeping and crawling +creatures. The shallow waters of the Tropics, +as a whole, however, do not possess a particularly +rich Fauna,—in fact, the distinguished +Dr Kükenthal, who has had great experience of +marine work, says that, in his opinion, the +Tropical seas are not richer in littoral animals +than the Arctic seas. Between the reef and the +sea-beach there is a lagoon, of varying breadth, +with a sandy bottom, which is almost as barren +of animal life as a desert. A few Worms and +Crabs, here and there a Star-fish and some shells +of Foraminifers, are all the spoils which fall to the +bag of the naturalist after many hours’ wading +on this unprofitable ground. The reason for this +is, perhaps, not far to seek. When the tide goes +down many stretches of sand are left dry, and +others retain only a few inches of water. The +exposure to the heat of a Tropical sun soon kills +and dries up any living animal that is unable to +burrow deeply in the sand, and the water in the +shallow pools rises in temperature to a degree +that the human hand or foot can only just bear, +so that the little Fish that escape into them run +the risk of being slowly cooked alive.</p> + +<p>On the inside of the lagoon there is, in many +places, a broad belt of Mangrove trees, forming +the “Mangrove-swamp,” which contains some interesting +and important animals. These trees +have a peculiar spreading and branching system +<span class="pagenum" id="Page_74">[Pg 74]</span> +of roots which are left exposed when the tide +goes down, and form with one another a kind of +network or web a foot or more above the ground, +upon which it is possible, with care, to walk +from place to place, at low tide. Between the +roots there is a slimy black sand or ooze, sometimes +hard enough to walk upon, but more +commonly soft and treacherous. At high tide +the water rises to a height of two or three +feet, completely covering the roots and giving +the swamp the appearance of a forest growing +in the sea. Of the animals, aërial and terrestrial, +that haunt the swamps it is not necessary +to say more than a few words, although they +too form a study of great interest to the enthusiastic +naturalist. But the marine zoologist +who visits the swamps cannot fail to take note of +the millions of Ants, Flies and Mosquitoes which +torment him at every step, and make a prolonged +stay an impossibility.</p> + +<figure class="figcenter illowp100" id="fig24" style="max-width: 30.625em;"> +<img alt="" class="w100" src="images/fig24.jpg" id="img_images_fig24.jpg"> +<figcaption> +<span class="smcap">Fig. 24</span><br> +<span class="small">Periophthalmus.</span> +</figcaption> +</figure> + +<p>One of the first creatures to be seen on entering +a Mangrove-swamp at low tide is a curious +little Fish called <i>Periophthalmus</i>. In some places +hundreds may be seen at one time resting on the +roots of the Mangroves, or skipping over the +pools of water from one root to another. There +are many varieties of <i>Periophthalmus</i> in different +<span class="pagenum" id="Page_75">[Pg 75]</span> +parts of the world, and their habits are not +exactly the same, so, to give an accurate description, +our attention will be confined to the form +occurring in N. Celebes. This little Fish is +about three inches in length and remarkable for +its very peculiar eyes, which are of a bright +yellow colour, situated quite close together on +the top of the head, and projecting so much from +their sockets that the outline of more than two-thirds +of the eye-ball can be seen. These eyes +are extraordinarily moveable, and frequently revolve +quite independently of one another, like +the eyes of a Chamæleon, giving the animal a +most grotesque and even ludicrous expression. +These Fish seem to swim in the water very +seldom; when undisturbed they may be seen +clinging to rocks or trees by their fore-fins with +their tails only in the water, but from time to +time they spring into the air to catch a Fly on +the wing, or a small Crab which has come unwarily +within their range. Their fore-fins are +peculiarly adapted to their habits, in that they +have a very muscular base and a distinct elbow +joint.</p> + +<p>These creatures are not easy to capture, as the +ground on which they live is not adapted for rapid +pursuit, and it is impossible to get close enough +to them to catch them in a hand-net with a long +handle. When kept in an aquarium it is seen +that although they are rapid swimmers when +they do go below the surface, they seem to prefer +to live with their head and shoulders out of the +water; and when chased in their natural haunts +they very rarely, if ever, seek to escape by +<span class="pagenum" id="Page_76">[Pg 76]</span> +plunging into the water, but they execute a +series of rapid jumps with extraordinary rapidity +from root to root or rock to rock, and so +avoid their pursuers. Their existence is really +an amphibious one, and their food consists partly +of Insects on the wing. Their gills are very +much reduced in size, and it seems probable, +from observations that have been recently made, +that their respiration is partly carried on by the +thin skin between the rays of the tail-fin.</p> + +<p>Another animal extremely abundant in the +Mangrove-swamps of Celebes, and, like <i>Periophthalmus</i>, +having a very wide distribution in +similar places in other tropical countries, is the +“Caller-crab” <i>Gelasimus</i>. These Crabs are about +an inch in breadth across the back, and are remarkable +for possessing one very much enlarged +and brightly-coloured claw, the others being +normal in size and dull in colour like the rest of +the body. On first entering the swamp at low +tide there may be seen on the mud between +the roots of the trees a number of bright yellow, +blue or green objects, which, as the traveller +approaches, disappear one by one into holes in +the ground. When the eyes are accustomed to +the gloom of the swamp these bright objects are +seen to be the great claws of the “Caller-crabs,” +the rest of the body being inconspicuous owing +to its close resemblance in colour to the slimy +ground.</p> + +<p>These are the principal and most abundant +marine inhabitants of the swamps, and as has +been pointed out, all of them are more or less +amphibious in habit. More locally distributed, +<span class="pagenum" id="Page_77">[Pg 77]</span> +Oysters and other bivalves may be found attached +to the roots of the trees. Several species of +marsh Gastropods occur, some of them in great +abundance in a few localities. Occasionally a +Sea-anemone, with remarkable powers of burrowing +rapidly in the sand when disturbed, may be +found, and to the microscopist a harvest of +Foraminifers and other minute forms of life +awaits investigation and description in the Mangrove-swamp.</p> + +<p>Whenever the tide is high a considerable +number of Fish-fry, Jelly-fish, and other forms +of floating and swimming life characteristic of +these waters, drift into the swamps; and some +being caught by the tangle of roots are left +behind, either in the pools, or high and moderately +dry upon the sand when the tide ebbs. +Upon these victims of the retreating tide swarms +of Ants and Flies descend from the trees, Crabs +from the shore and from their holes in the sand +are on the watch for them, Kingfishers and +Sandpipers are ready to pounce upon those which +are most to their taste, so that before the friendly +waters of the ocean return to the swamp, scarcely +one of them is left.</p> + +<p>These constitute what may be called in the +swamp the <i>extraneous</i> Fauna, which if it is not +truly indigenous is nevertheless necessary for the +continued existence and well-being of the true +inhabitants.</p> + +<p>The character of the sea-bottom on the outer +side of the living Coral-reefs varies so much in +different parts of the world that an adequate +treatment of the Fauna in that region would +<span class="pagenum" id="Page_78">[Pg 78]</span> +have to be one of greater length than is possible +in this book.</p> + +<p>The living edge of the Coral-reef is in some +cases situated on the top of a submarine precipice +of very considerable height, and in many +places the sounding-line goes down to a depth of +five or six hundred feet a few yards beyond the +limits of the reef. The practical difficulties in the +way of determining the character of the Fauna +of any sea-bottom that shelves in this manner +are very great, but where it is partly composed +of massive lumps of solid Coral they are at +present insurmountable. Every time the dredge +or trawl reaches the bottom it becomes entangled +in the Coral branches, and is liable to be seriously +torn, or even lost. Swabs and iron hooks and +fish traps may yield some scraps of information, +but speaking generally, the Fauna of these steep +slopes is scarcely known at all.</p> + +<p>The most important question, from the geological +point of view, that has to be determined is +the depth of water in which reef-building Corals +can live and thrive. This is still a matter of uncertainty +owing to the practical difficulties met with +in the attempts to investigate it. Darwin estimated +that the limit of vigorous coral growth +was between 20 and 30 fathoms, but in recent +years, owing to the discovery of luxurious Coral +patches in 44 fathoms on the Tizard and Macclesfield +banks, there is a pretty general opinion that +his estimate is too low.</p> + +<p>Whatever the exact limit may be, it is quite +clear that in many parts of the world the sea-bottom +quite close to the outer edge of the reef +<span class="pagenum" id="Page_79">[Pg 79]</span> +cannot support a vigorous Coral fauna. Here +and there patches of peculiar deep-sea species of +Corals occur, but they do not form in such depths +anything of the nature of a reef. They are +usually isolated specimens, similar to those that are +found in deep water on the Norwegian coast and +other parts of the world outside the limits of the +Tropics; but these specimens really belong to the +deep-sea Fauna, of which we shall learn more in +another chapter.</p> + +<p>In many places, however, the water at the +base of the outer edge of the reef is not very +deep, and may slope away gradually towards +the bed of the ocean. The Fauna of such slopes +in the Tropics is not characteristically rich, as +my own experiences of dredging in such waters +have proved. Time after time the dredge that +was used in 15 to 20 fathoms off the coast of +Talisse, came up with nothing but sand or +gravel. Occasionally a Brittle-star or a branch +of dead Coral, with a few Zoophytes growing +on it, came up; and in some places a few +beautiful Lily-stars or Crinoids relieved the +monotony of the investigation. But, on the +whole, the animals found in this region were +not numerous, nor of a character to excite any +particular interest.</p> + +<p>Before bringing this chapter to a close, a brief +reference must be made to one of the most remarkable +phenomena in the animal kingdom,—this +is the history of the Palolo worm. On certain +parts of the coast of the Samoan islands the +Palolo worm appears in great abundance in the +early morning hours of one or two days at the +<span class="pagenum" id="Page_80">[Pg 80]</span> +beginning of the third quarter of the moon in +the months of October and November. As the +worm is regarded as a very great delicacy by the +natives, the day of its appearance is looked upon +as one of the most important red-letter days of +the year. Weeks before the worms are expected +the advent of the Palolo is discussed, stories +are told of the fisheries of bye-gone years, anecdotes +of the last year are remembered and rehearsed, +and the whole population is prepared +for the great event as for a feast.</p> + +<p>When the grand day arrives the boats are +decorated, the girls put on all their finery, and +everyone who can find a seat in a boat goes off +to the fishery amid a merry chorus of song and +laughter. It must, indeed, be a strange sight to +see the flotilla of canoes with their eagerly expectant +and gaily-bedecked crews, waiting in the +dim light of the half moon for the day to break +and the exciting fishery to begin. As soon as it +is light enough to see into the water, a few +writhing Worms may be distinguished at the +surface, which increase in number with such extraordinary +rapidity, that in a little while it is +impossible to see anything below three or four +inches owing to the multitude of Palolos. As +quickly as possible the fishery proceeds, every +man, woman, and child gathering the harvest of +Worms during the precious moments of the sunrise. +When at last the sun rises well above the +horizon the Worm disappears again, and the +boats hasten to the shores with their booty.</p> + +<p>This remarkable swarming process of the +Palolo, occurring as it does, only once or twice +<span class="pagenum" id="Page_81">[Pg 81]</span> +a year, in constant relation with a particular +phase of the moon, and lasting on each occasion +only a few minutes in time, is not the only noteworthy +feature of the animal.</p> + +<p>The Palolo worm, as it is caught, varies in +length from an inch to a foot or more, and is +about a quarter of an inch in breadth, but it readily +breaks up into pieces when handled. It is composed +of numerous rings or segments, each provided +with a pair of processes bearing bristles, +but there is no head. Astonishing as it may +seem to those unacquainted with the natural +history of Worms, it is nevertheless a fact that +when the Palolo swarms it leaves its head behind +among the Corals, where, in all probability, it +regenerates a new body. This accounts for the +fact that while the body of the Palolo is frequently +brought home to our Museums in England, +its head is a rarity. The colour of the +Worm varies very considerably. The pieces +bearing eggs are usually of some shade of green, +hence the specific name <i>Palolo viridis</i> that is given +to it by scientists, but the males are usually +white. In connection with the appearance of the +Worm there is a curious statement that once in +every four years it is exactly one lunar month +late, so that the time of year of its occurrence is +constant. The natives are also forewarned of the +advent of the Palolo worm by the movements of +the land Crabs, which, it is reported, come down +from the fields and forest a few days before the +Palolo feast and plunge into the sea.</p> + +<p>The precise habitat of the Worm when it is +not swarming is still a matter of some doubt. +<span class="pagenum" id="Page_82">[Pg 82]</span> +A few rare specimens have been found in the +Coral blocks in shallow water, but it is generally +supposed that the majority of them live in deep +water on the outer side of the reefs. It is not +confined by any means to Samoa. It occurs also +in Fiji, Tonga and other Pacific islands. A +Worm similar to the Palolo in habits was described +years ago by Rumphius in the Malay +Archipelago, and Saville Kent mentions a little +Nereid worm with similar spawning habits on +the great Barrier-reef of Queensland.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_IV">CHAPTER IV. +<br><span class="medium">SURFACE-SWIMMING FAUNA (INVERTEBRATES).</span></h2> +</div> + +<p>Everyone of an observant turn of mind must +have noticed that in the wake of a boat that is +passing through the water on a calm summer’s +night, sparks of bright phosphorescent light may +be seen to appear, to remain for a few seconds, +and then become extinguished again. Sometimes +the breaking of the ripples on the surface of +the water seems to be sufficient to cause these +sparks to appear, but occasionally streaks and +flashes of pale blue light arise and disappear +without apparently any such mechanical disturbance.</p> + +<p>The phosphorescence of the sea, as this phenomenon +is called, is common enough on our coasts, +but it never reaches the degree of brilliancy and +beauty which is so remarkable in the open Atlantic +Ocean, the South Seas, and some other parts +<span class="pagenum" id="Page_83">[Pg 83]</span> +of the world. In the Atlantic Ocean the phosphorescence +is sometimes so bright that it is +possible to read a book on deck by its light +alone; and on a dark night in the Banda seas +the water is often like a huge expanse of pale +blue smoke studded with diamonds and other +lustrous gems.</p> + +<p>These lights are mainly produced by animals +which float and drift about on the surface of the +water. It is not, as is very commonly supposed, +only one or two different kinds of animals that +are phosphorescent, but a vast number belonging +to many widely different families and of a great +variety of form and structure. When the day +breaks many of these animals sink down a few +fathoms into the darker and cooler strata of +water, but a considerable number remain so close +to the surface that they can be easily caught in a +muslin net dragged after a boat.</p> + +<p>Some of these animals, such as the Jelly-fish, +can, during the day, be observed clearly enough +from the boat, others can only be seen when the +contents of the net are emptied into a glass bottle, +and others again are so minute that it requires a +strong magnifying glass to detect them at all. Such +animals that float or drift in the water without +powers of swimming vigorously in one direction +or the other, are collectively called the Plankton. +In every sea, from the Arctic regions to the +Equator, a Plankton will be found. Sometimes +it is mainly composed of one species, in other +cases it consists of many different species living +together. Under certain conditions the water +is simply crowded with these organisms, and in +<span class="pagenum" id="Page_84">[Pg 84]</span> +different circumstances the Plankton is represented +by only a few individuals.</p> + +<p>The variations of the Plankton in different +parts of the world have, of recent years, been +subjected to many searching investigations, but +although many important facts have been recorded, +the explanation of the principal phenomena +remains a mystery.</p> + +<p>One of the most interesting facts, perhaps, is +the extraordinary local variations to be observed. +To give a single example as an illustration of this +point the case of the common white Jelly-fish +may be mentioned. On occasions the surface of +the water in our bays and estuaries contains so +many of these animals, that the sea appears to be +little more than a mass of jelly. In other seasons +not more than a few isolated individuals will be +seen all through the summer months.</p> + +<p>With all the resources of modern scientific +investigation no adequate explanation has been +given to account for this fact. It may be that +the variation is due to the prevailing winds or +tides, to the temperature of the water, to the +roughness or smoothness of the sea, to disturbance +of the ground where the eggs have settled, +or to some other hitherto unforeseen conditions. +Not only seasonal, however, but even diurnal +variations occur, of a most remarkable and inexplicable +character.</p> + +<p>On one occasion for example I was collecting +a number of Jelly-fish in Southampton Water, +and for nearly two hours specimens were obtained +as fast as they could be hauled into the +boat. Suddenly a change came, and in a few +<span class="pagenum" id="Page_85">[Pg 85]</span> +moments the water that had been alive with +these animals seemed to contain not one. Another +time, after dredging nearly all the afternoon +at Lulworth for <i>Hormiphora</i>, with the very +poor success of a half dozen specimens, the net +came up simply choked full of these little round +jelly-like Ctenophores, and for the remaining +hours of day-light there appeared to be an +abundance of them all along the coast. One +morning in the Tropics, at about an hour after +sunrise, I was looking over the side of a steam-boat, +and saw that the surface waters were +full of beautiful and rare species of floating +animals. In less than half an hour afterwards, +when a boat was put off, scarcely one of them +could be found. Anybody who is accustomed +to working with a tow-net can give similar +experiences.</p> + +<p>In each of these cases a simple explanation +might be suggested. In the first case it might +have been the change in the tide which effected +the disappearance of the Jelly-fish; in the second +it might have been the approach of nightfall +that caused the Hormiphoras to rise; and in +the last case it might have been the approach of +the heat of day; but when carefully considered +such explanations are not sufficient, in that they +do not account for the suddenness of the change.</p> + +<p>The fact is that the conditions of life in the +surface waters are so complicated that it is extremely +difficult for us to accurately estimate +the balance of the forces which act upon these +organisms. The direct heat of the sun, the light +of both the sun and the moon, the tranquillity +<span class="pagenum" id="Page_86">[Pg 86]</span> +or roughness of the sea, the conditions of the +tides and winds which cause changes in the +surface temperature of the water, independently +of the direct heat of the sun, all influence the +delicate tissues of which these animals’ bodies +are composed, and cause them to change their +position.</p> + +<p>The animals which compose the surface Plankton +may be considered under two heads—those +that are adult, and those that are the larvæ of +sessile and crawling forms of life which in the +adult stage live at the bottom.</p> + +<p>Those belonging to the former group frequently +occur far out in the open ocean as well as in the +neighbourhood of the land, and have as a rule a +wide geographical distribution. Those belonging +to the latter group are more usually found within +a few miles of the coast line, although winds and +tides may occasionally drift them far out into the +sea, where their larval existence is prolonged for +an abnormally long time. Leaving out of consideration +for the moment the many interesting +exceptions, we may say that the Plankton of the +open oceans differs from that of the neighbourhood +of the coasts, by the larger proportion of +adult forms that it bears.</p> + +<p>A great variety of animals pass the whole of +their lives in the surface waters of the sea, but the +commonest and most widely distributed of all +probably are the Copepods belonging to the class +<i>Crustacea</i>.</p> + +<p>The Copepods are minute creatures, rarely +exceeding a quarter of an inch in length, which +row themselves through the water by a pair of +<span class="pagenum" id="Page_87">[Pg 87]</span> +long antennæ, projecting from the head end of +the body. They occur in fresh water as well as in +the sea, and so abundant are they that if a glass +tumbler be filled with the water from a pond, a +lake, or the sea, and examined with a magnifying +glass, a number of specimens are almost sure +to be seen. They occur in abundance at the +surface of the sea in nearly all climes, and very +often are the sole representatives of the Plankton +that are found in the hauls of the tow-net.</p> + +<p>Attention has already been called above to +the fact that in the Tropics the surface-floating +animals gradually sink down into the depths +as the heat of the day approaches, but even on +fine calm days a few Copepods will be found at +the surface. Although they sometimes occur in +Temperate seas in such vast numbers that the +water is quite discoloured with them, more +variety of form, or, in other words, more distinct +genera and species are found in the warm and +Tropical parts of the world.</p> + +<p>The study of this group reveals to the microscopist +some of the most marvellously beautiful +displays of colour and form that can be found in +the animal kingdom. Sometimes the body and +legs are beset with an immense number of +extremely fine and delicate spines, which are +in some cases provided with rows of still +finer spinelets, giving them the appearance of +a most minute feather. Sometimes the body +contains large granules of a bright red colour, +and at others smaller granules of a bright +blue are seen scattered among the organs. The +<span class="pagenum" id="Page_88">[Pg 88]</span> +female Copepods usually carry, securely fastened +to their tails, two little pear-shaped sacks of +eggs, which are sometimes bright green, blue +or red.</p> + +<figure class="figcenter illowp97" id="fig25" style="max-width: 26.1875em;"> +<img alt="" class="w100" src="images/fig25.jpg" id="img_images_fig25.jpg"> +<figcaption> +<span class="smcap">Fig. 25</span><br> +<span class="small">A free-swimming Copepod.</span> +</figcaption> +</figure> + +<p>Endless are the varieties of form and colour +presented by these little creatures, and endless +are the beauties which the study of their structure +reveals; but as we have mentioned them +first as inhabitants of the surface waters of the +seas, we must pause to consider here how these +organisms, which excite so much wonder and admiration, +are adapted or fitted for their peculiar +mode of life. But it must be remarked that +these statements apply only to the free-swimming +Copepods, for many animals classed in this group +by zoologists are parasites, and as such are so profoundly +<span class="pagenum" id="Page_89">[Pg 89]</span> +changed that they might at first sight +be relegated to another class of organisms altogether.</p> + +<p>Now we must remember that animals that live +in the surface waters must be prepared to keep +afloat for the whole period of their lives—from +the time they are hatched until they fall a prey +to some voracious enemy. Under ordinary circumstances, +they never find an opportunity of +resting, either on the sea-bottom or on any floating +substance.</p> + +<p>If a Copepod is watched in a tumbler of water +it will be seen to give a number of strokes with +its long antennæ and then to rest suspended for +a few seconds; a few more strokes follow and +then another pause, and so on. During the +period of rest the body sinks slowly, sometimes +almost imperceptibly, but never so much that it +cannot recover its position in the water after the +first few strokes.</p> + +<p>It must be clear to the reader that the less +it sinks during the pause the less will be the +muscular activity required to regain its position, +and that, consequently, every mechanical contrivance +that its body possesses to diminish its +tendency to sink will be a saving of muscular +and nervous energy.</p> + +<p>A very simple experiment will demonstrate +that a body which presents a considerable surface +to the water, sinks more slowly than one +of the same weight that is round and compact. +If we take two equal pieces of silver paper and +roll one of them into a tight little ball, leaving +the other as a flat sheet, and then let them sink +<span class="pagenum" id="Page_90">[Pg 90]</span> +together in a tall jar of water, the former will +reach the bottom long before the latter. Similarly +the body of an animal which possesses a +dense armature of spines, as it presents more +surface to the water, sinks much more slowly +than the body of an animal of the same weight +that is smooth and compact.</p> + +<p>The spininess or hairiness of the Copepod body, +then, may be regarded as one of its adaptations +to the environment in which it lives. But of +course this character is not by any means confined +to the Copepods. Very many of the surface-swimming +Crustaceans, and more particularly +their larvæ, have remarkably spiny bodies, and +among many of the Foraminifers, Radiolarians, +Worms, Molluscs and even Fish we find some +similar extension of the surface of the body +which lowers the sinking rate. Another means +by which the bodies of many of the animals composing +the Plankton are buoyed up, is the secretion +into a special chamber or reservoir of some +gas or oil of a lesser weight than the sea-water. +This is what may be called the balloon principle. +In such animals we may regard the heavy +muscles, skeleton, skin and viscera as the car +and the freight of the balloon, while the gas +reservoir corresponds to the whole silk case containing +the coal-gas.</p> + +<p>Such an animal might also be compared to a +man in the sea clinging to an india-rubber life-belt. +The body of the man by itself is heavier +than the water, and in the absence of the muscular +exercise of swimming sinks rapidly to the bottom; +but the body of the man and the life-belt taken +<span class="pagenum" id="Page_91">[Pg 91]</span> +together are lighter than water and float continuously +without any action of the muscles. +If the life-belt were considerably smaller than +usual the man and belt would sink, but much +less rapidly than the man alone; and the muscular +energy required to keep himself afloat would +be far less with the belt than without it, consequently +he would be able to keep afloat much +longer with the same expenditure of muscular +energy. The bodies of many of these surface-swimming +animals may then be best compared +with a man assisted by a <i>small</i> life-belt. When +dead or still they slowly sink, but a slight +amount of muscular energy expended in swimming +is sufficient to keep them afloat. In what has +been said above about the body of the Copepod, +reference has been made to certain bright red +granules. These are in all probability little +globules of some oily or fatty substance lighter +in weight than the sea-water, which serve to +buoy up the body of the little creature. It is +difficult to say why they should have such bright +colours. We have no record of observations +that show that the colours can be of any use +to them as a protection from their enemies, +nor is there any physical explanation of the +colours of these granules any more than of the +blood, the bile and other products of animal +and vegetable vital processes. The eggs contained +in the egg-sacks of the Copepods also +bear a certain amount of oily substance very +frequently different in colour from that of the +other parts of the body, and this probably +acts in the same manner upon the body of the +<span class="pagenum" id="Page_92">[Pg 92]</span> +parent or on that of the little larvæ when they +are first hatched.</p> + +<p>Thus we find in the body of the Copepods at +least two important modifications of structure, +which render them fit or suitable for their life-long +swim in the surface waters of the sea.</p> + +<p>Let us now consider another important group +that has the same habit but differs from the +Copepods in size and form, namely, the Jelly-fish.</p> + +<p>The Jelly-fish, or Medusæ, as they are usually +called by zoologists, are disc or bell-shaped animals +of a very soft gelatinous texture. From the +centre of the disc or bell there hangs down a tube +of varying length bearing the mouth, and the +margin is often provided with a row of thin +delicate tentacles like a fringe. (See <a href='#fig7'>Fig. 7</a>). +When watched on a calm summer’s evening they +may be seen to slowly sink a few inches or more +from the surface, and then with a series of convulsive +contractions of the bell to rise to the +surface again. Sometimes these contractions +may be observed to continue perfectly rhythmically +for a long time.</p> + +<p>In one of the commonest of the English +Medusæ four rings of a bright pink or orange +colour may be observed in the disc. These are +eggs and male spawn, and when shed they give +rise to multitudes of tiny little larvæ which sink +to the bottom and become fixed to some rock or sea-weed. +After the larva has securely fixed itself +it becomes changed into a little Polyp which +gives rise, in the course of time, to a number of +small discs, arranged one above another like a +<span class="pagenum" id="Page_93">[Pg 93]</span> +pile of saucers. These discs break away from the +base and from the parent stock to grow into the +form and size of the adult Jelly-fish.</p> + +<p>We have here an example in the life-history +of the common Jelly-fish, of what is known as +“alternation of generations.” The eggs give +rise to sessile Polyps, and these produce a +number of buds which, when fully grown, give +rise in their turn to the eggs; or, in other +words, the egg-producing generation of large +surface-swimming Jelly-fish regularly alternates +with the small sedentary bud-producing generation. +Now as the bud-producing or Polyp +generation of the common Jelly-fish referred to +is fixed to the bottom, the proximity to a coast, +or at any rate to a shallow water area, is a +necessity for the continuation of the species. +Many of the Jelly-fish are undoubtedly drifted +out into the open ocean by the tides, but the +larvæ they produce, after swimming about in +search of something solid to which they can +attach themselves, must at last perish. It is +only those larvæ which are hatched near enough +to the shore to be able to reach the bottom +during the tenure of their lives, that can continue +the generation of these Jelly-fishes.</p> + +<p>But even in the open ocean far away from +shallow water or a coast line, Jelly-fish, belonging +of course to different species from those of the +coasts, are found. What is their natural history? +How is their life different from that of the +Jelly-fish of the shore? Some of them produce +larvæ very similar to those described above but +they seek, instead of the rocks or sea-weed, other +<span class="pagenum" id="Page_94">[Pg 94]</span> +Jelly-fish and attach themselves to them as +parasites.</p> + +<p>In other species, however, the “alternation of +generations” is entirely lost, and the egg gives +rise directly to a free-swimming little Jelly-fish +which in time grows to be like its parent in +size and shape. In this case the fixed or sessile +form in the life-history is, as it were, omitted in +order that the animal may lead a life independent +of the coast and sea-bottom.</p> + +<p>The Jelly-fish, then, present us with an interesting +example of a manner in which the life-history +of an animal may be modified for or +adapted to this surface-swimming habit.</p> + +<p>There is also another point of interest +about these creatures in this connection. In +writing about the Copepods I pointed out the +mechanical contrivances they exhibit for keeping +themselves afloat, namely, the spines, hairs and +oil globules. Jelly-fish have neither spines nor +oil globules of the same nature, but still their +bodies are very light in the water and in the +absence of muscular movements sink but slowly +to the bottom. This lightness is due to the fact +that all the tissues and organs of which it is +composed are very largely distended with water. +When the body of a Jelly-fish is analysed it is +found that over 95 per cent. of it consists of +water. This power of absorbing large quantities +of fluid into the tissues, while it increases the size +of the body, proportionately diminishes its weight +in water.</p> + +<p>It has also another effect. It makes the +tissues of the body much more transparent and +<span class="pagenum" id="Page_95">[Pg 95]</span> +gives them that soft jelly-like consistency which +is so characteristic of the surface-swimming +forms.</p> + +<p>The popular term 'Jelly-fish’ is one that is +frequently applied to many forms of surface-swimming +animals that are really very different +in structure and general composition from the +true Medusæ. The Salps, for example, to which +reference will be made presently, although soft +and transparent in texture like the Medusæ, +belong to a very widely separated group of +animals, and to the anatomist it would be as +absurd to classify them together, as to put the +Butterflies and the Fish in the same group.</p> + +<p>These remarks are necessary because in the +treatment adopted in this little book the animals +that live together are considered in the same +chapter, and it is important that the reader +should bear in mind that they are not as a +consequence anatomically related to one another.</p> + +<p>It is indeed remarkable that animals which +are so different from one another, in their +anatomy, development and life-history, as, for +example, the Salps and the Medusæ, and which +have had such a widely different ancestry, +should, as a matter of fact, resemble one +another so closely in form and texture as to be +given collectively the same name by the unscientific +observer.</p> + +<p>Among the heterogeneous crowd of animals +that are popularly called Jelly-fish there is one +particular group which presents us with some +very interesting members. These are the +Siphonophores. In many parts of the temperate +<span class="pagenum" id="Page_96">[Pg 96]</span> +and warmer seas of the world the surface may +be covered with thousands of little creatures +which, when brought upon the deck, seem to be +little else than coloured bladders of air. The +scientific name of these animals is <i>Physalia</i>. +When placed in a glass of water, however, it +will be seen that, from the under side of the +bladder which floats freely on the water, +numerous delicate tentacles and Polyps hang +down. These creatures are kept at the surface +by an air-bladder float and no muscular energy +is required to sustain them in that position.</p> + +<figure class="figcenter illowp100" id="fig26" style="max-width: 23.1875em;"> +<img alt="" class="w100" src="images/fig26.jpg" id="img_images_fig26.jpg"> +<figcaption> +<span class="smcap">Fig. 26</span><br> +<span class="small">The swim-bladder of Velella.</span> +</figcaption> +</figure> + +<p>Another Siphonophore called Velella has a +bladder of a more complicated character in the +shape of a disc +with a semi-circular +or +triangular sail +on its upper +side. There +can be no +doubt of the +advantage of +this float to the species. It not only enables +them to keep afloat without the expenditure +of muscular energy, but as the wind catches the +sail they are drifted along over great areas of +the ocean and thus distributed far and wide from +the spot on which they were hatched. Still +the float has undoubtedly its disadvantages, for +it exposes them to the danger of being blown +ashore by a steady wind and so perishing in +thousands. Agassiz says that on the coast of +Florida the beach is sometimes marked with +<span class="pagenum" id="Page_97">[Pg 97]</span> +lines of Velellas that have been stranded in this +manner, and I have seen in Celebes four or five +rows of bright blue Physalias stretching for miles +along the shore.</p> + +<p>In the Mediterranean and Eastern Atlantic +Ocean a very large Physalia occurs which has +received the popular name of the “Portuguese +man-of-war,” and is famous for its stinging +powers. The stinging is produced by a number +of very minute sacs, which shoot out, when they +are touched, a long pointed thread that penetrates +the skin and conveys an irritant poison. These +are called the thread-cells, and the “Portuguese +man-of-war” is not by any means peculiar in possessing +them. All the Medusæ and Siphonophores, +all the true Corals and Sea-anemones have +them—in fact, all those creatures which are classified +together by the zoologist as <i>Cœlenterata</i> may +be said to be stinging animals. The thread-cells, +however, vary very much in size in this group, +and in the great majority of cases the thread is +too feeble to perforate the skin of the human +hand, and consequently their owners have not +acquired a bad reputation.</p> + +<p>People do not warn their children not to touch +the Sea-anemones on the rocks or the Jelly-fish +stranded on the beach, and yet they are both +dependent for their food upon their stinging +powers; and indeed many of the British Medusæ +which may be handled with impunity, are capable +of stinging quite severely the more delicate skin of +the back and arms of unwary bathers.</p> + +<p>Besides the two forms of Siphonophores which +have been described, there are many others to be +<span class="pagenum" id="Page_98">[Pg 98]</span> +found at or near the surface of the seas +of all climes. Some of them possess great +floats like Physalia and Velella, but the majority +of them have either no floats at all or such as are +too small to do more than assist in keeping the +animal near the surface. All of these Siphonophores +are provided with little bells, which, contracting +rhythmically like a Jelly-fish, drag the +animal along, sometimes to the surface, sometimes +a few fathoms below it. Some of these forms are +extremely graceful, being like long strings of +jelly, with numerous clusters of Polyps and long +feathery tentacles, towed through the water by +one or two exquisitely delicate little bells situated +at the leading end of the string.</p> + +<p>A few words must now be said about the Salps, +because in some seas the water is on occasions so +full of them that they seem to be packed together +ready for preserving. The simplest form of Salp +is like a small sac or barrel of transparent gelatinous +substance open at both ends. Running +round the barrel are five or seven bands of a less +transparent nature, appearing to the unaided +vision like milky white streaks. These streaks +are bands of muscles by which the movement of +the body through the water is assisted. Sometimes +they are seen swimming about independently +of one another, sometimes Salps very similar +to them in general appearance are seen to be +attached to one another in long chains. At first +it was supposed by naturalists that the former or +Solitary Salps were of a different species to the +latter, or Chain-salps as they are called; but it +has been discovered that these two forms are but +<span class="pagenum" id="Page_99">[Pg 99]</span> +stages in the life-history of one species. When +the anatomy of a Chain-salp is minutely examined +it is found to contain a single egg, which gives rise +to a young Salp similar in nearly all details to the +solitary one. This escapes from its parent’s body +when it is old enough to take care of itself, and +leads an independent existence. After it has +grown to its full size it gives rise to a stalk +which divides up into a number of young Salps, +attached to one another in a +very characteristic manner.</p> + +<figure class="figcenter illowp40" id="fig27" style="max-width: 9.9375em;"> +<img alt="" class="w100" src="images/fig27.jpg" id="img_images_fig27.jpg"> +<figcaption> +<span class="smcap">Fig. 27</span><br> +<span class="small">Solitary form of Salp, bearing a young stalk of Chain-salps.</span> +</figcaption> +</figure> + +<p>Here, then, we have another +instance of alternation of +generations similar in this +respect to the example previously +quoted among the +Jelly-fish, in that the one +generation produces an egg, +and the other numerous buds; +but differing from it in the fact +that in the case of the Salps +both generations are adapted +for freely swimming at the +surface of the sea.</p> + +<p>Space does not allow us to say more in detail +about the other animals of the Plankton that +belong to the same group as the Salps; of the +wonderfully interesting life-history of <i>Doliolum</i>; +of the extraordinary bright light emitted by +<i>Pyrosoma</i>, or of the remarkable little <i>Fritillaria</i>, +shaped like a tad-pole, living in its house of jelly. +The story of each of these might take a whole +chapter to itself and still be only partly told.</p> + +<p>Anyone who is acquainted with the general +<span class="pagenum" id="Page_100">[Pg 100]</span> +appearance of the Whelks and Periwinkles, and +other Gastropods of our shores might be well +astonished when he saw, for the first time, many +of the Gastropods of the high seas. The shell is +either absent altogether or consists of a thin +little papery cap far too small to afford protection +to the body. The head and foot, and, indeed, +the greater part of the body, are transparent, +soft and gelatinous like a Jelly-fish, in fact the +whole appearance is so different that it is not until +the internal anatomy is carefully studied that +their true position in the animal kingdom can be +assigned to them.</p> + +<p>Here, then, we find another instance of a profound +modification of structure associated with +the surface-swimming habit; the modification +being due very largely to the absorption of considerable +quantities of water into the tissues of +the body, which has the effect of rendering them +transparent, and, at the same time, of reducing +their weight in the water.</p> + +<p>The transparency of the body of so many of +the animals of the Plankton has suggested the +theory that by rendering them less conspicuous +to their enemies it is of the nature of a protection +to them. We ought to hesitate before accepting +this theory until we know more accurately what +are the enemies that they endeavour to protect +themselves against. It is very probable that +none of the Fish will feed upon any of the transparent +Jelly-fish, neither is there any evidence +that the Salps and the pelagic Gastropods form +a favourite food for them. There is no good +reason for supposing that the Sea-birds would, if +<span class="pagenum" id="Page_101">[Pg 101]</span> +they could see them better, prey upon them, so +long as there are Fish in the sea to provide a +more substantial and satisfactory meal. The +Whales, as they dash through the water with +their huge mouths wide open, undoubtedly +swallow them in thousands, but it can not be +reasonably supposed that the Whale can be +guided by sight in the selection of its food. +We ought not, perhaps, to go so far as to +say that it is no protection to them, for Prof. +Moseley states that the Turtle sometimes feeds +upon the Velellas, but at the same time we may +consider that the transparency is an effect produced +by the large amount of water in their +tissues, which is there for the purpose of reducing +their specific +gravity and assisting +in that manner in their +floatation.</p> + +<figure class="figcenter illowp73" id="fig28" style="max-width: 16.8125em;"> +<img alt="" class="w100" src="images/fig28.jpg" id="img_images_fig28.jpg"> +<figcaption> +<span class="smcap">Fig. 28</span><br> +<span class="small">Pteropod, showing the so-called wings.</span> +</figcaption> +</figure> + +<p>The only Gastropod +found in the open seas +which retains in its +characteristic form the +large coiled shell, is +the beautiful blue +<i>Janthina</i>, famous for +its habit of constructing +a little raft which +floats on the surface +of the sea. To the +underside of this it attaches its eggs and spends +its life in pushing or dragging the raft about.</p> + +<p>No account of the Molluscs of the Plankton +would be complete without some reference to +<span class="pagenum" id="Page_102">[Pg 102]</span> +the Pteropods. These creatures are provided +with a pair of muscular lobes of the body, which +have been compared to wings. By means of +these they are able to swim through the water. +Some of them are provided with delicate little +glassy shells, but in others the body is quite +naked. We may regard the Pteropods as +the most highly modified forms of Gastropods +adapted for a pelagic life.</p> + +<p>In both the Arctic and Antarctic seas this +group occurs in immense numbers, and it is +supposed to form not an inconsiderable proportion +of the food of the gigantic Right-whales. +They also occur in the Temperate and +Tropical zones, and indeed there are actually +more genera and species there than in the colder +regions to the North and South.</p> + +<p>The Insect world is represented at the surface +of the ocean by a curious little Bug called <i>Halobates</i>. +It is not uncommonly found in tropical +or subtropical seas feeding upon dead Salps or +Jelly-fish, and when disturbed scuds over the +surface after the manner of many of the Insects +living on our inland ponds and lakes. It has +been described as an “ivory-legged fellow, +covered with a bluish-white down.” As it is +essentially an air-breather like all adult insects, +its usual habitat is '<i>on</i>’ the sea and not <i>in</i> it, so +that strictly speaking it is not a member of the +Plankton. There is no doubt that under certain +circumstances it can and does dive into the +water, and on these occasions it carries with it +for respiratory purposes a layer of air attached +to the 'bluish-white down’ covering the body. +<span class="pagenum" id="Page_103">[Pg 103]</span></p> + +<p>There are no traces of wings on its thorax, +and it is therefore incapable of flight. Very +little is known at present of its development, and +practically nothing of its internal anatomy, so +that its proper position in the order of the Bugs +or <i>Hemiptera</i> is a matter of conjecture, but it is +an interesting little creature, in the fact that it is +the only member of its class that has a purely +pelagic life-history.</p> + +<p>Among the microscopic forms of life found in +the Plankton of the sea, the Radiolarians and +Foraminifers are perhaps the most important. +The Radiolarians are very minute specks of protoplasm, +usually protected or supported by an +elaborate skeleton of a substance closely allied to +flint. The form of this skeleton varies so much +in the numerous species that have been described, +that it is quite impossible in a few words to give +an adequate idea of the principal types. (See +<a href='#fig2'>Fig. 2</a>). We may say, however, that in a considerable +number of them the skeleton has the +form of a hollow sphere, perforated by numerous +round holes and supporting outside a number of +long thin needles. The anatomy of the Radiolarians +is extremely simple. Their bodies are built +entirely of protoplasm which performs all the vital +functions. There is no definite head, mouth, +brain, nor muscular organ. This being the case, +the question arises, How do these animals provided +with a skeleton of such a heavy substance +as flint manage to support themselves in the water +without muscular appendages? The answer to this +question is two-fold—In the first place, the elaborate +form of the skeleton presents an enormous +<span class="pagenum" id="Page_104">[Pg 104]</span> +surface to the water in proportion to its weight, +and consequently sinks slowly; and secondly, +the protoplasm is provided with numerous +vacuoles containing a watery fluid, and in many +cases at least one larger vacuole containing oil. +If the liquids in these vacuoles are lighter than +sea-water, and there is good reason to suppose +that some at least +of them are, then +they are of the same +nature as the oil +chambers of the +Copepods, and are +hydrostatic in function.</p> + +<figure class="figcenter illowp59" id="fig29" style="max-width: 19.625em;"> +<img alt="" class="w100" src="images/fig29.jpg" id="img_images_fig29.jpg"> +<figcaption> +<span class="smcap">Fig. 29</span><br> +<span class="small">Shells of Foraminifers living at the bottom of the sea.</span> +</figcaption> +</figure> + +<p>Among the Foraminifers +very few +genera strictly belong +to the surface +Fauna. Most of +them have heavy, +compact shells of +carbonate of lime, +and they live among +the sand or the rocks +at the bottom of the +sea. The best known +of the surface-dwelling forms is <i>Globigerina</i>, and +this, in accordance with its habits, possesses a +shell which, like that of the Radiolarians, is very +light, perforated by numerous large holes and +provided with long delicate spines. The shell +of <i>Globigerina</i> might well be mistaken for that +of a Radiolarian were it not for the fact that +<span class="pagenum" id="Page_105">[Pg 105]</span> +it is composed of carbonate of lime instead of +flint.</p> + +<p>The Radiolarians in some waters, and the +<i>Globigerinidæ</i> in others, are present in enormous +numbers, and as they die their shells fall in a +gentle rain from the surface towards the sea-bottom, +where they frequently, form a very large +part of the abysmal mud.</p> + +<p>In speaking of the organisms of the surface of +the sea no mention has yet been made of the +plant world. Of the large conspicuous Sea-weeds +<span class="pagenum" id="Page_106">[Pg 106]</span> +that are often found far out in the open ocean +the best known is the Sargasso or Gulf-weed of +the Atlantic. It forms in some cases great +floating patches, of very considerable area, and +is, when alive, of a bright yellow colour. The +Sargasso patches are, however, of great interest +to the zoologist, because they support a considerable +population of animals specially adapted by +their form and colour to live among the Sea-weeds. +They present us, in fact, with a peculiar +Fauna, containing representatives of all the most +important groups of marine animals.</p> + +<p>Besides the large conspicuous weeds like the +Sargasso, the surface of the sea supports a large +Flora of minute plants of very lowly organisation, +and it is not at all uncommon for them to be +present in such numbers as to cause a distinct +discolouration of the water.</p> + +<figure class="figcenter illowp58" id="fig30" style="max-width: 23.875em;"> +<img alt="" class="w100" src="images/fig30.jpg" id="img_images_fig30.jpg"> +<figcaption> +<span class="smcap">Fig. 30</span><br> +<span class="small">Globigerina living at the surface of the sea.</span> +</figcaption> +</figure> + +<p>The banks that they form on the coast of +Brazil and elsewhere were called “Sea-sawdust” +by Sir Joseph Banks. Moseley says that “when +tracts of the sea are passed through, which are +full of this <i>Trichodesmium</i>, the water lighted up +by sunlight, when looked down into, appears +as if full of small particles of mica or some such +substance, so strongly is the light reflected from +the minute bundles of the Algæ”; and again, he +says, “so abundant is <i>Trichodesmium</i> in some seas +that one of the explanations of the name of the +Red Sea is that the term was derived from the +discolouration of the water by vast quantities of +<i>Trichodesmium erythræum</i>.”</p> + +<p>In addition to this “Sea-sawdust,” Diatoms, +the still more minute organisms, the Bacteria, +<span class="pagenum" id="Page_107">[Pg 107]</span> +and the debateable particles called Coccospheres +and Rhabdospheres, add to the number of the +floating Flora of the seas.</p> + +<p>The importance of these organisms to the +zoologist is that they must ultimately form the +food supply of the animals of the Plankton. +Some of the larger animals may feed upon the +smaller ones, and the smaller ones may, in their +turn, feed upon still smaller ones, but we must +come eventually, in descending the scale, to the +animals that are vegetable-feeders and prey upon +the minute plants that have just been mentioned.</p> + +<p>Now that we have considered very briefly +some of the principal forms of life that compose +the floating and drifting population of the surface, +we may return to the subject with which +the chapter opened, namely, the phosphorescence +of the sea.</p> + +<p>It need hardly be mentioned that it is a subject +which is beset by innumerable difficulties. +Even when the sea is extremely phosphorescent, +and the observer is provided with an excellent +microscope and all the necessary scientific appliances, +he finds it difficult to answer the question—“What +is the cause of the phosphorescence tonight?” +The sample of water he takes may +reveal to him a multitude of different organisms, +many of which are so small that they can only +be seen with a strong artificial light, and then it +is impossible to say which are and which are not +phosphorescent.</p> + +<p>Some of the Copepods are known to possess +an organ emitting a blight blue star-like light +which shines for a time and is then suddenly extinguished. +<span class="pagenum" id="Page_108">[Pg 108]</span> +In the Malay Archipelago several +of these bright lights may be seen near the surface +of the water on calm mornings just before +sunrise, and it is extremely interesting to watch +them gradually sinking down into deeper water +as the day dawns, and then suddenly going out +one after the other.</p> + +<p>Some of the large Jelly-fishes, such as <i>Pelagia +noctiluca</i>, glow with a soft blue light. The curious +pelagic Tunicate colony <i>Pyrosoma</i> receives its +name from the fact that it emits a bright light. +A giant <i>Pyrosoma</i> was caught by the <i>Challenger</i> +in the deep-sea trawl, and, to quote the words of +Professor Moseley once more, “It was like a +great sac, with walls of jelly about an inch in thickness. +It was four feet in length and ten inches +in diameter. When a Pyrosoma is stimulated by +having its surface touched, the phosphorescent +light breaks out at first at the spot stimulated, +and then spreads over the surface of the colony +as the stimulus is transmitted to the surrounding +animals. I wrote my name with my finger on +the surface of the giant Pyrosoma as it lay in a +tub at night, and the name came out in a few +seconds in letters of fire.”</p> + +<p>All of these animals are sufficiently large to be +easily seen by the naked eye, and the phenomena +of their phosphorescence can be carefully observed. +But many of the more minute forms of +life also exhibit this peculiarity, and contribute +in no small degree to the bright light of the sea.</p> + +<p>For instance, when the sea on our coasts +shows a dull blue light, flashing into greater intensity +where the ripples break, it will be found +<span class="pagenum" id="Page_109">[Pg 109]</span> +to contain immense numbers of very minute +creatures called <i>Noctiluca</i>. Each of these has a +gelatinous consistency, and is the shape of a +microscopic cherry, bearing a short whip-like +process, called the flagellum, which propels the +organism slowly through the water. There +seems to be no doubt that, on these occasions, +the light is caused by these <i>Noctilucas</i>, but there +are many other minute forms which abound on +the surface and give off a pale phosphorescent +light at night.</p> + +<p>We do not know for certain what may be the +use of the phosphorescent light to the organisms +that possess the power of emitting it. If we +assume that the transparency of the bodies of +the pelagic animals has a protective value in +the day-light, it is difficult to understand why +many of them should become so attractive, +as the phosphorescent light makes them, at +night. It is probable that the star-like lights +of many of the Copepods may serve to attract +to one another the two sexes, as it does with +the Glow-worms and Fire-flies, but such an explanation +as this cannot well be accepted in the +case of <i>Pyrosoma</i>, which is hermaphrodite, or the +<i>Noctilucas</i>, which live together in immense numbers. +There can be little doubt, however, that +there is some good reason for it, as it occurs in +so many different animals belonging to widely +separated families.</p> + +<p>In the neighbourhood of coasts or in shallow +water, the surface of the sea usually supports +a very large number of animals in a larval +or immature state. These creatures live only +<span class="pagenum" id="Page_110">[Pg 110]</span> +a portion of their lives in a free-swimming +condition, and then a change occurs during +which they sink to the bottom and gradually +assume the adult characters.</p> + +<p>Nearly everybody is acquainted with the +general appearance of the Crab and Star-fish, +but few would guess that the young stages of +these animals are to be found among the minute +transparent floating Fauna of the surface waters +of the sea.</p> + +<p>The habits of the young and of the old, of +these animals are widely different; the former +must constantly support themselves in the +water, they must feed upon and have means +for catching and devouring minute floating +organisms and must in other ways be adapted +for life with the Plankton; the latter being +unable to swim are capital crawlers and walkers +over the rocks and sand of the bottom, have +heavy bodies which sink rapidly in the water +and, in other ways, are adapted for life with +the shallow water Benthos.</p> + +<p>The conditions of life at the surface and at +the bottom being, as I have previously pointed +out, so different and the adaptations of structure to +suit each set of conditions so great, we have, as +a result, a long series of animals in which the +young larval stages of life are absolutely +unlike the adult and mature stages.</p> + +<p>No better examples to illustrate these changes +could be given than those chosen from the group +of the Echinoderms. Take, for instance, the +common Star-fish with its thick heavy skin +studded with plates of carbonate of lime, and +<span class="pagenum" id="Page_111">[Pg 111]</span> +its dense opaque body drawn out into five +finger-like processes. These features of the +animal indicate at once that its life is spent +crawling on the sand or rocks at the bottom of +the sea. If a Star-fish that has been caught in +a lobster pot or brought to the surface attached +to the bait on a fishing line, is cast into the sea +it sinks to the bottom at once without any +apparent effort to swim, to keep afloat, or to +arrest its rapid descent. It is therefore clearly +unfitted for a surface-swimming existence, but +its eggs give rise to larvæ which are admirably +adapted to it, and can indeed only +exist at or near the surface of the +sea. These larvæ are, as a rule, +when first hatched, covered with a +number of very minute vibratile +cilia, by means of which they swim +with considerable rapidity through +the water. After a time a number +of bands appear, which are covered +by specially long cilia and then the +smaller cilia on the intervals between +the bands disappear.</p> + +<figure class="figcenter illowp49" id="fig31" style="max-width: 12.125em;"> +<img alt="" class="w100" src="images/fig31.jpg" id="img_images_fig31.jpg"> +<figcaption> +<span class="smcap">Fig. 31</span><br> +<span class="small">Young larva of a star-fish before the Brachiolaria stage is reached.</span> +</figcaption> +</figure> + +<p>The precise arrangement of the bands differs +in the different species, but from being at first +perfectly circular in contour they become more +and more curved and twisted, sometimes fusing +with one another and in parts degenerating, +until, at last, when the larval stage reaches its +full development, the bands have assumed an +elaborate and somewhat fantastic pattern.</p> + +<p>The body of the larva is, like that of so many +surface-swimming creatures, extremely transparent. +<span class="pagenum" id="Page_112">[Pg 112]</span> +The uniform oval shape which it has +when first hatched becomes changed as it +develops by the formation of a certain number +of short blunt processes or arms, and it was +the presence of these which caused the older +naturalists to call this larva the Brachiolaria.</p> + +<p>If one of these minute Brachiolaria larvæ +be caught and examined with a microscope it +is not difficult to see that it has a little round +mouth leading into a short digestive canal +which opens to the exterior by a vent. It is +therefore clearly capable of feeding itself and +leading a perfectly independent existence. In +the older larvæ there will be noticed an appearance +which has, under a low magnifying power, +the form of an incomplete and rather opaque +ring round the stomach. This opaque ring +becomes larger and larger, it exhibits five projections +radiating from its centre, and at last gives +rise to all the organs of the fully formed Star-fish. +As the ring develops the larva sinks from the +surface and loses the power of independent +feeding, and then, when all is ready, the skin is +cast off and a small but perfectly formed +Star-fish emerges.</p> + +<p>The Trepangs, the Brittle-stars, the Sea-urchins +and other Echinoderms have, as a general rule, +life-histories similar to that of the Star-fish, but +there is one point of difference in detail which +is of sufficient interest to be mentioned before +passing on. The larva of the Brittle-stars and of +some of the Sea-urchins has a number of arms +which are much longer, in proportion to the +whole size of the larva, than they are in the +<span class="pagenum" id="Page_113">[Pg 113]</span> +Brachiolaria, and on account of the manner in +which these arms are inclined towards the apex, +the larva has a rough resemblance to the form +of a painter’s easel. This type of larva is called +the Pluteus. The main point of interest about +the Pluteus, however, is that the arms are supported +by delicate bars of carbonate of lime which +are connected together at the apex and form a +very definite larval skeleton.</p> + +<figure class="figcenter illowp61" id="fig32" style="max-width: 17.375em;"> +<img alt="" class="w100" src="images/fig32.jpg" id="img_images_fig32.jpg"> +<figcaption> +<span class="smcap">Fig. 32</span><br> +<span class="small">Pluteus larva.</span> +</figcaption> +</figure> + +<p>This larval skeleton is cast off with the skin +when the metamorphosis takes place, and it is +consequently of great interest to scientists in the +fact that it is one of those structures which are +formed to meet the exigencies +of larval life only, and is perfectly +useless for the adult. In +considering the manifold questions +which arise in the study +of the relation of animals to +their surroundings we are often +inclined to fix our attention too +exclusively upon the adaptations +that are manifested in +the adult form. In the case +of some classes in which the immature stages of +life are passed through very rapidly and under +the protection of the parents, this is not to be +deprecated; but in most cases it is important to +remember that in the struggle for existence there +is such danger of extermination that each stage +of life may have acquired special characters for +adaptation to its particular mode of existence. +The peculiar markings and colours of the Caterpillars +is a familiar example of the special +<span class="pagenum" id="Page_114">[Pg 114]</span> +characters of larval forms among terrestrial and +air-breathing animals, but in none of these do we +find so great a specialisation in larval characters +as in some of the marine forms of life.</p> + +<p>It is said above that the Echinoderms as a +general rule have free-swimming larvæ, but there +are exceptional cases which have an interest for us +quite as great as that of the ordinary life-history.</p> + +<p>Many Echinoderms are found living in very +great depths of the ocean and it is difficult for +us to believe that any of these can have pelagic +larvæ similar to those of their shallow water +relatives. The difference in pressure between +that of the bottom of the deep-sea and of the surface +is, by itself, sufficient to convince us that a +delicate organism like a Brachiolaria or Pluteus +could not make the upward journey unharmed; +but when we add to that the great distance of +two or even three miles in a direct line, the difference +in temperature and in light, we must +realise that the ordinary transformations of the +shallow water Echinoderms is an impossibility +for the deep-sea varieties.</p> + +<p>As a matter of fact we know very little about +the life-history of deep-sea Echinoderms, and this +is not a matter for wonder when the reader reflects +upon the great difficulties that have to +be overcome in obtaining a few specimens of the +adult forms; but at least one of the Star-fish of +the Abyss has been found to bear little pouches +or pits in which the young are fostered until +they are ready to lead an independent life in the +form of the parents.</p> + +<p>It has also been shown that in some of the +<span class="pagenum" id="Page_115">[Pg 115]</span> +Arctic Star-fishes the larval life is in a similar +manner abbreviated and protected, and it seems +probable that this may be accounted for by the +fact that the surface waters, where the larval +forms would live if they were liberated, are for +very long periods covered with ice.</p> + +<p>The great group of the Crustaceans also presents +us with many interesting larval forms specially +adapted to surface life. In a previous chapter +I have pointed out that the Barnacles of our +coast give birth to curious little free-swimming, +six-legged larvæ called Nauplii, which after having +undergone two or three further changes, +settle down on a rock and assume the adult +features (see <a href='#fig12'>Fig. 12</a>).</p> + +<p>It is not known how long these changes take +in the ordinary course of nature, but it is quite +probable that the larval life is a comparatively +short one.</p> + +<p>Some Barnacles, however, live far out at sea +on drifting wood or parasitic on the skin of +Whales, and it is reasonable to suppose that +when their larvæ are hatched a very considerable +time may elapse before they find a suitable +resting-place to complete their metamorphosis.</p> + +<p>The life-histories of these species are not at +present accurately known, but a few remarkable +Nauplii have been found which, there is reason +to believe, are really the Nauplii of some kind +of Barnacle and are specially adapted to a long +life at the surface by the enormous length of +their spines.</p> + +<p>In the specimen discovered by Chun in the +<span class="pagenum" id="Page_116">[Pg 116]</span> +Canary Islands, of which a figure is given here, +the spines were seven or eight times the length +of the body, the eye was remarkably small, and +the muscles were feebly developed. It may be +that this is the larva of some species of Barnacle, +which, from the character of the host or home +where it lives when adult, must be prepared to +wait a long time in its larval +habitat before the chance +comes for it to find a suitable +resting-place.</p> + +<figure class="figcenter illowp85" id="fig33" style="max-width: 29.3125em;"> +<img alt="" class="w100" src="images/fig33.jpg" id="img_images_fig33.jpg"> +<figcaption> +<span class="smcap">Fig. 33</span><br> +<span class="small">Long-spined Barnacle-nauplius.</span> +</figcaption> +</figure> + +<p>Many of the +Crabs and Prawns +have remarkable +larvæ, characterised either by two or +three extremely long spines or in some +cases by a festoon of shorter and many +branched spinous processes spreading out +from their carapace, tail and limbs. +These spines may be regarded partly as +a device for assisting in the floatation of the +body, and partly, perhaps, as a protection +against some of the creatures that feed upon +them; but in both respects they are special +larval adaptations to the pelagic life. It is +extremely interesting to find that in this class +of animals the same characters are not constant +<span class="pagenum" id="Page_117">[Pg 117]</span> +in the larvæ. A Prawn called <i>Palinurus</i> has a +larva the body of which becomes extremely expanded +and flattened, so as to resemble a very +thin sheet of glass, the eyes and the limbs at the +same time undergoing remarkable modifications. +Another larva becomes extraordinarily distended +by the absorption of water into its tissues so as +to resemble in texture a small Jelly-fish.</p> + +<p>A great deal more might be said about the +story of Crustacean larvæ, as it is one which +is full of interest and wonder, but throughout +the whole of it we see, wherever there is a +larval history at all, that some one or more of +those characteristic features have been evolved, +which were previously noted in adult animals as +an adaptation to their free-swimming pelagic life.</p> + +<p>In many other groups of marine animals we +find the same alternation of a transparent larval +life at the surface and an opaque adult life at the +bottom.</p> + +<p>The Oysters, Clams and Mussels, the Winkles +and other Gastropods, the Worms, the Sponges +and many other forms of life that creep among +the Sea-weeds and are fixed upon the rocks or +burrow in the sand, produce exquisite and delicate +transparent little larvæ which for a certain length +of time at least float and drift about in the light +of the sunshine in the surface water. They have, +of course, many varieties of form and many peculiar +organs for locomotion and floatation, so that +it is possible for a competent zoologist to tell +without much difficulty the group of animals, if +not the actual genus and species, to which any +particular larva belongs. +<span class="pagenum" id="Page_118">[Pg 118]</span></p> + +<p>It might be thought that, as so many of the +animals living near the coast line in shallow +water have pelagic larvæ, the Plankton of the +neighbourhood of the coasts would differ from +that of the open oceans in the fact that a considerable +proportion of it consists of these larval +forms. But many of the larvæ seem to be able to +live a long time without further change than an +increase in size, and being drifted out to sea by +the winds and tides are often found in the open +ocean at very great distances from any coast line.</p> + +<p>It would be interesting to know more of these +larvæ which go thus astray. How long can they +go on waiting for the opportunity to cast off their +childish clothes and assume the garments of the +adult? Do they in time undergo changes which +bring about a kind of childish old age, or do they +suddenly perish with all the characters of youth +upon them?</p> + +<p>These and many other questions connected +with this most fascinating chapter in the story of +the sea have still to be answered by the investigations +of scientific men in the future.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_V">CHAPTER V. +<br><span class="medium">SURFACE-SWIMMING FAUNA (VERTEBRATES).</span></h2> +</div> + +<p>In the preceding chapter we have considered +only those animals of the surface of the sea, +which, owing either to their small size or the +transparency of their bodies, are not as a rule +conspicuous to a passenger on board a mail-steamer. +<span class="pagenum" id="Page_119">[Pg 119]</span> +Such a passenger might cross the +ocean many times without realising in the least +the wealth of animal life that there is in every +wave that breaks upon the ship, and yet be impressed +with what he has seen of the Whales +and Porpoises, the Sharks, Bonitos and Flying-fish.</p> + +<p>It is to these groups of animals that a few +lines must be devoted before closing our story +of the surface-swimming Fauna. If the young +and immature stages be for the moment left out +of consideration, it may be said that nearly all +the Fish and all the Whales and Porpoises are +large, opaque in appearance, and perfectly conspicuous. +Moreover, they are all strong and +rapid swimmers, capable of roaming over wide +areas of the sea in search of prey, and independent +of, except in so far as their prey are influenced +by, the currents and winds. It is clear +that they cannot be said to 'float’ and 'drift’ +about in the ocean, and consequently they do +not strictly belong to the Plankton. The term +used in speaking of them collectively is the +Nekton, which means the swimming population.</p> + +<p>The greatest number of the Fish of the sea +are shore Fish; that is to say, they habitually +feed at, or close to, the bottom of the shallow +waters near the coasts or sunken banks.</p> + +<p>But there is a very considerable number that +are strictly pelagic, living and feeding far away +from the shores, bringing forth their young alive, +or shedding floating eggs, and in every way independent +of the shore and of the bottom. +<span class="pagenum" id="Page_120">[Pg 120]</span></p> + +<p>It is difficult to give any general features by +which they are characterised, as so much variety +may be observed among them; but as a general +rule they are elongated in form, round or oval +in section, in colour green or gray above, with +silvery white bellies. Some of these, such as +the Flying-fish and the Flying-gurnard, are +capable of making very considerable flights in +the air, their pectoral fins being enormously +elongated, and when fully expanded somewhat +similar to the wing of an Insect.</p> + +<p>The Flying-fish occur in shoals in nearly +all tropical and subtropical seas. When disturbed +by a ship on a calm day it is said that +they spring out of the sea, expand their fins, +describe a regular parabolic curve in the air, and +then fall with a splash into the water. There is +a considerable controversy raging on the question +of the use of their fins in this flight through the +air, some observers believing that the fins are +used only as a kind of parachute, and others that +they are used like wings for raising the body +above the water. It is very difficult to decide +which view is correct.</p> + +<p>In the Indian Ocean I watched the Flying-fish +for several days during rather rough weather, +and my impression was most distinctly that in +the middle of the flight the fins are vigorously +flapped four or five times, the flapping being +followed by a decided rise in the air. On the +other hand, it may be that this flapping appearance +is caused by the wind catching the +wings in a certain position, and not by the +muscles of the fish. Whether the flying is +<span class="pagenum" id="Page_121">[Pg 121]</span> +actually assisted by the flapping of the wings +or not, it is certain that the Fish do rise in +gusty weather to a very considerable height, +frequently falling on to the decks of steamers +twenty feet above the water line.</p> + +<p>At night, these Fish fly at the ships and not +away from them, as they do in the day-time, and +the natives in some parts of the Malay Archipelago +catch them in large numbers by holding +up a torch by the side of a large sheet, when the +Fish flying at the bright light and striking against +it, fall into the bottom of the canoe. Flying-fish +are excellent to eat, their flesh being similar in +taste to that of the Herring, but an epicure would +probably say that it is not quite so good.</p> + +<p>The Bonito is a fish occurring over a wide area +of the tropical and temperate seas, which sometimes +makes tremendous jumps out of the water. +I have seen it frequently on the coast of Celebes +jump to a height which I roughly estimated as +at least fifteen feet. It is said to feed upon the +Flying-fish, and it is probable that it has acquired +the power of springing out of the water in the +pursuit of its prey.</p> + +<p>The pelagic Fish, which has acquired the +widest reputation, and that an evil one, is the +“blue-Shark.” This occurs in the tropical and +occasionally in temperate seas. Its usual size is +from twelve to fifteen feet, but, according to Dr +Günther, individuals of twenty-five and more feet +are occasionally captured. It is extremely voracious, +attacking anything of a fleshy nature that +it observes in the water.</p> + +<p>One of the most remarkable animals of the +<span class="pagenum" id="Page_122">[Pg 122]</span> +open ocean is the Sun-fish. It has a very wide +distribution in the tropical and temperate regions. +In the adult condition it is almost circular in +outline and considerably flattened from side to +side like a John Dory. It sometimes reaches a +size of eight feet in diameter and +a very great weight. From the +little that is known of its development +it apparently undergoes +some extraordinary changes +in shape before it reaches the +adult form.</p> + +<figure class="figcenter illowp64" id="fig34" style="max-width: 27.375em;"> +<img alt="" class="w100" src="images/fig34.jpg" id="img_images_fig34.jpg"> +<figcaption> +<span class="smcap">Fig. 34</span><br> +<span class="small">The Sun-fish.</span> +</figcaption> +</figure> + +<p>In addition to these and +several other Fish of a large size which may be +found at the surface of the open ocean, there are +several species known to science which never +grow to a length of more than a few inches. +<span class="pagenum" id="Page_123">[Pg 123]</span> +Many of these are characterised by remarkably +long fin rays, by their large eyes, or by other +features which may be regarded as special modifications +for their peculiar habits.</p> + +<p>A very interesting genus is <i>Scopelus</i>, which is +found very widely distributed in tropical and +other seas. Some of the species live in very deep +water, and are purely abysmal in habit, but most +of them rise to the surface at night, when they +may be caught in immense numbers. In form +they are not unlike a small Sprat, but they +exhibit on each side of the body a series of +minute eye-like organs, which emit a phosphorescent +light.</p> + +<p>In addition to these Fish which are found far +out in the open ocean, there are several genera, +which form an important feature of the surface +waters in the neighbourhood of the coasts. +Among them we find such valuable food-fish as +the Herrings, Sprats, Mackerels, and Pilchards.</p> + +<p>The complete history of the Herring has yet +to be written, for, notwithstanding the laborious +investigations of several naturalists, working +independently, or as officers of the Marine +Biological Association and similar Institutions, +there are some facts and stages which have, up +to the present time, escaped observation.</p> + +<p>The Herring species is divided into a number +of races, which, differing from one another only +slightly in anatomical characters, have different +seasons for depositing their eggs. This fact +has only recently been thoroughly established; +and while it assists us greatly in the task of +completing the history of the Fish, it definitely +<span class="pagenum" id="Page_124">[Pg 124]</span> +destroys the validity of many theories which +were prevalent among fishermen and others before +the days of the more exact scientific treatment +of fishery questions.</p> + +<p>It is well-known that from the end of the +month of June to December immense shoals of +Herrings are found in the North Sea. It is quite +impossible to estimate the numbers of Fish in +these shoals, but they are so great that if they +could be counted it would probably be found +that the Fish that are annually caught by all the +fishing boats, form but an insignificant fraction +of the whole. All of these Fish are in such a +condition that it is evident their spawning time +is close at hand. When they are ready they +approach the coasts, the exact time varying +according to the race of Herrings, and the spawn +is deposited on or close to the ground, the eggs +becoming attached to stones and other objects on +the bottom. After the Herrings have spawned, +they seem to disperse, or, at any rate, to disappear +from the surface waters of the North Sea. +What actually becomes of these shoals of spent +Herrings is not known, but it is a fact that in +the spring there are so few Herrings to be found +in the narrower part of the North Sea that it +does not pay the fishing boats to go after them. +It is possible, however, that, after the spawning +process, the Herrings migrate to the deeper +water of the Norwegian coasts, in order to feed +on the Crustaceans and other forms of life that +are to be found there in abundance.</p> + +<p>The Mackerel do not apparently make such +extensive migrations as the Herrings. They +<span class="pagenum" id="Page_125">[Pg 125]</span> +spawn in the open sea, five or ten miles from the +coast, during the spring time. The egg of the +Mackerel, unlike that of the Herring, does not +sink to the bottom when it is spawned, but, being +provided with a large oil globule, it is light +enough to remain on the surface until the young +larva is hatched. After the spawning has taken +place the Mackerel approach the coast, and will +even enter bays and narrow inlets on the shores +in pursuit of the young Sprats and other small +Fish upon which they prey.</p> + +<p>A great deal could be written on the history +of the Pilchards, the Anchovies, the Sprats, and +other Fish which frequent the surface waters of +the sea in the neighbourhood of the European +coasts. No two species seem to have precisely +the same habits, and what is known +about them presents us with many curious +and remarkably interesting facts. For further +details, however, I must refer the reader +to the larger and more comprehensive books +dealing specially with the subject, for space +must still be found for a few words on another +group of animals which play a conspicuous part +in the story of life in the seas.</p> + +<p>The animals composing the class of Mammals +are distinguished from other Vertebrates by the +fact that the females are capable of providing +milk for their young ones after birth. Most of the +Mammals are strictly terrestrial, but three orders, +namely, the <i>Cetacea</i>, the <i>Sirenia</i>, and the <i>Carnivora</i> +contribute to the surface-swimming population of +the sea.</p> + +<p>The <i>Cetacea</i> are all aquatic. The order includes +<span class="pagenum" id="Page_126">[Pg 126]</span> +the many genera of Whales, Porpoises +and Dolphins.</p> + +<p>The Right-whales are distinguished by the +enormous size of the mouth and the absence of +the little triangular fin in the middle of the back +which is found in the other Whales.</p> + +<p>These animals have no teeth in the adult +condition, but are provided with a series of +plates situated at the sides of the mouth which +are used as strainers to catch the small Pteropods +and other animals living in the water which +pass through the great gape. The plates are +composed of a substance called “Baleen,”—the +well-known whale-bone of commerce,—they are +triangular in shape, and frayed out into a +brush-like edge on the side that faces the cavity +of the mouth. The Greenland Right-whale attains +to a size of fifty feet in length when fully +grown, and it is usually found in shoals among +the ice floes of the far north.</p> + +<p>In former times many Right-whales belonging +to species allied to the Arctic form occurred in +the temperate regions of the Atlantic and Pacific +Oceans, but in consequence of the valuable +fishery they afforded they are now becoming +very scarce.</p> + +<p>The largest of all the Whales—in fact, the +largest existing animal—is the Blue-whale, which +attains to the enormous length of 86 feet. It +spends the winter in the open seas, and approaches +the coast of Norway in the spring.</p> + +<p>The Whales, like all the animals of the Class +to which they belong, are air-breathers. They +are able, however, to hold their breath for a +<span class="pagenum" id="Page_127">[Pg 127]</span> +considerable time under water. When they +come to the surface to renew the air-supply in +their lungs, they first make a violent expiratory +effort from the nostril, and drive a column of +spray many feet into the air above them. This +phenomenon is called by the whale fishers +“spouting,” and it was erroneously supposed +by them to be a column of water forced from the +mouth into the nostril, and then expelled at the +surface.</p> + +<p>The Dolphins and the Porpoises are distinguished +from the true Whales by the fact that +they are provided with teeth, on one or both of +their jaws, and there is no “whale-bone.”</p> + +<p>The Sperm-whale has probably been called a +“Whale” from its enormous size, but it is +anatomically very widely separated from the true +whales and more closely allied to the Dolphins. +It has no “whale-bone,” and the lower jaw is +provided with a row of sharp-pointed teeth set +in a groove in the bone. Its great value is due +to the fact that there is a large cavity situated +above the skull, containing an oily substance from +which “Spermaceti” is made.</p> + +<p>The principal food of these large “Toothed-whales” +seems to be Cuttlefishes, and the examination +of the contents of their stomachs, +which has been carried out on board the Prince +of Monaco’s private steam-ship when engaged on +a scientific cruise, has yielded some new forms of +these giant Molluscs. The Sperm-whales, however, +do not disdain a Fish diet as well.</p> + +<p>The Porpoises are found on our own coasts. +They may often be seen following the “schools” +<span class="pagenum" id="Page_128">[Pg 128]</span> +of Whales as they approach the coast in the +summer months, and they occasionally chase +their prey some distance up the estuaries of the +English rivers. The habit that Porpoises have +of accompanying ships for long distances affords +us many opportunities of watching their graceful +movements, and of estimating the very great +speed with which they can swim through the +water for hours at a stretch. It is difficult to +understand the meaning of this habit of following +ships. It has been suggested that the Porpoises +mistake the ship for a huge Sperm-whale, +and hope to benefit by stray morsels of large fish +that fall from its jaws. But this theory does not +account for the fact that the Porpoises so often +go in front of the ship. The following extract +from Darwin’s “Voyage of the Beagle” gives, in +a few words, a vivid picture of Porpoise life:—</p> + +<p>“In our passage to the Plata, we saw nothing +in particular, excepting on one day a great shoal +of Porpoises, many hundreds in number. The +whole sea was in places furrowed by them; and +a most extraordinary spectacle was presented, as +hundreds, proceeding together by jumps, in which +their whole bodies were exposed, thus cut the +water. When the ship was running nine knots +an hour, these animals could cross and recross the +bows with the greatest ease, and then dash away +right ahead.” This description reminds me very +forcibly of a sight I once saw in the Talaut +Islands, south of the Philippines. In passing +between two of the islands the strait seemed to +be alive with Porpoises tearing through the water +at a terrific pace. They accompanied the steamer +<span class="pagenum" id="Page_129">[Pg 129]</span> +for about six hours and then suddenly disappeared. +My impression was that they were attracted to +the ship not from a desire for more food, for +there was an abundance of Herrings in the straits +at the time, but from sheer curiosity. I think +the feeling of curiosity, that is to say, the desire +to go and look at something strange or unusual, +is much more prevalent among animals than we +generally suspect.</p> + +<figure class="figcenter illowp100" id="fig35" style="max-width: 32.9375em;"> +<img alt="" class="w100" src="images/fig35.jpg" id="img_images_fig35.jpg"> +<figcaption> +<span class="smcap">Fig. 35</span><br> +<span class="small">The common Porpoise.</span> +</figcaption> +</figure> + +<p>It is an interesting fact about the Porpoise +that, although it is so fish-like in shape, it should +present some features which remind us of the +Pig. The English word is probably derived from +the two French words <i>porc</i> and <i>poisson</i>, and +therefore means “Pig-fish.” The Germans call +it Meeresschwein, meaning “Sea-pig,” and the +Malay word for it is “Babi-laut,” which also +means “Sea-pig.” But if we make some allowance +for those who call these Cetaceans “Pigs,” +we must make none for those who call them +“Fish.”</p> + +<p>Like all the other members of their order the +Porpoises have a fish-like tail, but the flaps are +placed horizontally and not vertically as they are +in Fish. The skin is quite naked, having no +scales of any kind, and there are no gills or gill-openings. +<span class="pagenum" id="Page_130">[Pg 130]</span> +Like all other Mammals the Cetaceans +bring forth their young alive, suckle them, and +breathe air by means of lungs. But there can be +no doubt that they are extremely modified for +their aquatic life. The characteristic covering of +Mammals—the hairs—is, in the adult condition +of the Whales, entirely wanting, and is represented +in other members of the Class by only +a few bristles on the snout. The heat of the +body is maintained by a thick coat of fat, called +the blubber, lying immediately beneath the skin, +and this yields, on boiling, a valuable oil, which +helps to support the whale-fishermen. One of +the most striking modifications, however, is the +loss of the hind limbs. It is only in some species +that even rudiments of these have been found. +All of these facts indicate that the Cetaceans +must have taken to a mode of life in the water a +very long time ago, and the study of the rocks +proves the existence of Whales as far back as +Eocene times, but it is of interest to note that, +in some respects, the oldest fossil Cetaceans are +less specialised than those that are now living.</p> + +<p>The class of Mammals called the <i>Carnivora</i> +includes the Cats, Dogs, Ferrets and many other +animals which are purely terrestrial, but one of +its divisions is entirely composed of those well-known +aquatic animals the Seals and the Walrus. +If we take the common Seal as an example of +this group, and compare it with the Porpoise, as +a representative of the Cetaceans, we find that in +habits as well as in anatomy the former is less +completely changed than the latter. The Seal +frequently comes to land to bask in the sun, or +<span class="pagenum" id="Page_131">[Pg 131]</span> +to produce and care for its young, and it is +capable of making some progress over the rocks +by the help of its flipper-like fore-limbs; the +Porpoise, on the other hand, never leaves the +water of its own free will. Unlike the Porpoise +the body of the Seal is covered with a thick coat +of hairs, and the hind limbs are retained. Although +there is a general resemblance in the +form of the body between these two animals—this +form being, in all probability, mechanically +the best for rapid progress through the water—a +glance at their skeletons shows great and important +differences, which the merest tyro in +anatomy could point out. In expression, too, +there is a marked difference, for while the Porpoise +has a certain cast of countenance which, +when seen at a distance, deserves the epithet +“pig-faced,” the face of the Seal, with its large +round eyes, its small nose and high intelligent +brow, is almost human in expression.</p> + +<p>The Seal has a habit of raising its head above +the water and staring at an approaching boat, +and when doing this it may readily be mistaken +at first sight for a man overboard, but no one +could ever mistake a Porpoise for a human +being.</p> + +<p>The common Seal has a very wide range +occurring near the coast of both the Atlantic +and Pacific Oceans. It is found on some of the +more sequestered parts of the British shores, +but not in large numbers, for the common Seal, +unlike many of its allies, does not appear to +congregate in large shoals at any time of the +year. They are described as being timid, inoffensive +<span class="pagenum" id="Page_132">[Pg 132]</span> +creatures, easily tamed, passionately +fond of their children and taking an intelligent +interest in music.</p> + +<p>There are several animals closely related to +the Seal, occurring in different parts of the +world; and a few words may be said about the +remarkable animal called the “Sea-elephant,” +which is found on Kerguelen island in the +Antarctic Ocean. The popular name was +given to the animal in consequence of the +fleshy protuberant nose which has been compared +with the trunk of an Elephant and is +possessed only by the male. The late Professor +Moseley, who came across a small herd of them +when the <i>Challenger</i> was at Kerguelen, says: +“The trunk is produced by an inflation of a +loose tubular sac of skin placed above the +nostrils, just as is the 'Cap’ in the northern +Bladder-nose Seal. The trunk is evidently, as +appears from both the drawings, sacculated, and +hence irregular in form when inflated.”</p> + +<p>The Sea-lions and Sea-bears or the Eared +Seals, as they are sometimes called, form a very +distinct family. The one that is best known to +the general public is the Californian Sea-lion, as +it often lives in captivity in the European +menageries for many years and attracts the +attention of the visitors by the tricks which it +is taught to perform.</p> + +<p>In the spring months of the year these +creatures may be seen in great numbers on the +rocky islands off the coast of California, where +they come to breed.</p> + +<p>The most important of them all, from a +<span class="pagenum" id="Page_133">[Pg 133]</span> +commercial point of view, is the Fur-seal from +the Northern Pacific. In the month of May +these animals approach the Prybilov islands in +the East, or the Commander islands in the +West of the Behring Sea. The first to arrive on +the land are the old males. These choose for +themselves certain areas or 'homes’ on the +shore and fight desperately for their possession +with all who dare to come within their reach. +When matters are at length somewhat settled +the time arrives for the females to approach the +shore. The fighting then begins again with +renewed vigour, and desperate encounters take +place for the possession of a goodly stock of +wives for the season.</p> + +<p>There seems to be little in the way of courtship +in the domestic economy of the Fur-seals, the +wives being simply “captured” by the scruff of +their necks when they come within reach of a +would be husband, and retained in his harem +just so long as he can prevent any one of his +neighbours from stealing her. The Fur-seal, +like all his relations, is polygamous, but the +number of wives that each male appropriates to +himself seems to vary very considerably. Mr +Elliott mentions a case in which there were as +many as forty-five females in one home, but, as +a general rule, the number is much less. As +there is only one male to every twelve or +thirteen females, there are numerous males +over, which cannot found a home for themselves. +These bachelors, together with a number of the +young females, resort to a separate piece of +ground, where they spend their time in playing +<span class="pagenum" id="Page_134">[Pg 134]</span> +games. The play-grounds are however the scene +of the tragedies of Seal life, for they are resorted +to by the hunters, who slaughter immense +numbers of the larger males for the sake of +their valuable skins. As the skins of the old +male Seals are not of very much value and as it +is important, for the perpetuation of the race, to +preserve the females from injury, the breeding +grounds are usually not molested. It is therefore +the bachelor seal of from two to five or six +years of age that has to supply the market. +Those naturalists who have visited the Seal +rookeries on these islands say that the numbers +of these animals that can be seen at one time +is almost incredible. We can form some estimate +of them when we learn that over a hundred +thousand skins are exported from the Prybilov +islands alone every year.</p> + +<p>The Seals leave the rookeries in the month of +August, and after swimming about for some time +in the neighbourhood of the islands, eventually +depart into the open ocean in search of the food +their famished bodies need so much after the +fasting and fighting of the breeding months.</p> + +<p>The largest of all these aquatic Carnivores is +the Walrus, which lives within a short distance +of the shores of the lands in the Arctic regions. +It is easily distinguished from the Seals by +its great size, the males reaching a length of +10 or 12 feet, and by the enormous canine +teeth in the upper jaws, which project downwards +from the cover of the lips in the form of +two large pointed tusks. These tusks are used +for hoisting the bodies of the animals on to the +<span class="pagenum" id="Page_135">[Pg 135]</span> +ice, for digging in the sand in search of the +Mussels upon which they feed, and for general +fighting purposes.</p> + +<p>It is said that in former times the Walruses +lived in immense herds in regions much further +south than they do now; but the ravages of the +hunter, who chased them for their ivory tusks +and their oil, have driven them into regions +where they are rarely visited by anyone but the +Arctic explorer; and to those of my readers who +wish to learn more of their habits, I can but say +that in the pages of Dr Nansen’s book, “Farthest +North,” he will find the story of the Walrus +written in a manner which no man living could +have done more vividly and brilliantly than the +great Norwegian zoologist and explorer.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_VI">CHAPTER VI. +<br><span class="medium">DEEP-SEA FAUNA.</span></h2> +</div> + +<p>Some of the most important conditions under +which life at the bottom of the deep-sea occurs +have been mentioned in the first chapter. We +have pointed out that the pressure is enormous, +that the temperature is only a few degrees above +the freezing point, and that, except in those places +where phosphorescent animals emit a faint light, +it is absolutely dark, no rays of direct sunlight +being able to penetrate such a mass of water as +lies between the bottom of the ocean and its +surface.</p> + +<p>With such conditions to contend with it is not +<span class="pagenum" id="Page_136">[Pg 136]</span> +surprising that the naturalists at the beginning +of the century believed that no animals could +possibly live on the floor of the great oceans. +Their beliefs, however, merely afford us an +example of the danger of prophesying without +knowing, for the great expeditions which have +investigated the ocean-bed during the last thirty +years have proved the existence of a rich and +peculiar Fauna in all the great depths that have +been dredged. The general results of these investigations +have been recently summed up by +Dr John Murray in the last volume of the <i>Challenger</i> +Reports. He points out the extraordinary +variety of life in the deep sea as shown by the +contents of the dredge. “At Station 146 in the +Southern Ocean, at a depth of 1375 fathoms, the +200 specimens captured belonged to 59 genera +and 78 species.” He can find no record of +species equal to this in depths of under 50 +fathoms, and concludes that the evidence at +present before us is sufficient to warrant the +belief that the great depths of the ocean are as +a general rule extremely rich in species.</p> + +<p>From what has been already said, it may be +gathered that nearly all the most important +groups of marine animals have representatives +in the deep-sea. There are Fish, Tunicates, +Crustaceans, Molluscs, Echinoderms, Worms, +Cœlenterates and Protozoa. Nearly all of these +are so modified, either in form or colour, or the +structure of their organs of sense, or in other +particulars, that they could be recognised at once +in a collection as deep-sea animals; but there is +a small minority which seem to have undergone +<span class="pagenum" id="Page_137">[Pg 137]</span> +but little change in adapting themselves to their +strange environment.</p> + +<p>We may commence our study of this remarkable +Fauna by a few remarks on their colour. +The first and most striking feature is that the +animals are almost invariably uniform in colour. +If they are dark-brown they are dark-brown all +over, if they are red they rarely exhibit bands of +white or spots of blue. Moreover, they are +not always in harmony with the colour of their +surroundings.</p> + +<p>In the shallow waters the animals that live +among the green Sea-weeds are green, those that +live on the sand are coloured like the sand, and +many of those that live among the rocks are +darkly pigmented with black and blue. In +the abyss of the ocean, where there is any light +at all, the colour is, in all probability, fairly uniform +over wide tracts, and yet we may find in one +haul of the dredge, black Fish, red Crustaceans, +and purple Trepangs.</p> + +<p>There seems to be no particularly predominant +colour among the deep-sea animals. Most of +the Fish are black or dark-brown, but many +are light violet, some are pale rose and +others bright red. Among the Crustaceans +bright red seems to be the prevailing shade, +just as the darker tints of black and brown are +among the Fish.</p> + +<p>Among the Echinoderms we find white, purple, +yellow, red, and pink forms, and among the Jelly-fish +and Corals, red, violet, and green. In fact +it would be necessary to describe every class of +animals in turn, and then almost every genus in +<span class="pagenum" id="Page_138">[Pg 138]</span> +each class, to give an adequate idea of the +variety of colour met with in the Fauna of the +deep-sea.</p> + +<p>It is inconceivable that each of these animals +can live amid surroundings of a colour similar to +its own, and therefore we may without much +hesitation believe, that the colour of deep-sea +animals is not, as a general rule, of use as a +protection.</p> + +<p>Next to the peculiarities of colour, the most +striking features of the more highly organised +inhabitants of the bottom of the sea are the +modifications of the organs of special sense. +The Fish, the Crustaceans and the Molluscs +almost invariably exhibit some remarkable +modifications of the eyes. In their natural +haunts there must be either absolute darkness, +or the faint and usually intermittent light +emitted by phosphorescent animals. How intense +this light may be it is impossible to judge. +The light that is emitted by animals on the deck +of a ship can afford no criterion of the light they +emit under a pressure of two tons to the square +inch. However, the fact that the deep-sea +animals have either very large eyes or no eyes +at all, suggests forcibly that this light is not +sufficient to cause a general illumination.</p> + +<p>Some of the Fish are quite blind, and although +most of these have a very small and rudimentary +eye, in at least one Fish, <i>Ipnops</i>, which is +peculiar to deep water, no trace of an eye is +to be found.</p> + +<p>In some genera with a very wide distribution, +a very interesting series of stages may be +found, indicating the changes that may have +taken place in the history of the blind Fish of +the abyss. In the genus of deep-sea Cods +(<i>Macrurus</i>) for example, those species which live +in water of less than a thousand fathoms depth +have very large eyes, and those that are found +in greater depths have much smaller ones.</p> + +<p>The same in general is true of the Crustaceans. +The deep-sea Cray-fish have lost not only their +eyes, but also the stalks which supported them. +In <i>Bathynomus</i> (a Crustacean belonging to the +group <i>Isopoda</i>), however, there is a pair of +enormous eyes. +But as a rule +the eyes of +Crustaceans degenerate +and +disappear in +shallower water +than the eyes +of Fishes. At +depths of 500 +fathoms or +greater, the eyes of the Crustaceans usually show +signs of reduction in size or other retrogressive +changes, and in the greatest depths they are +nearly always wanting altogether.</p> + +<p><span class="pagenum" id="Page_139">[Pg 139]</span></p> + +<figure class="figcenter illowp59" id="fig36" style="max-width: 50em;"> +<img alt="" class="w100" src="images/fig36.jpg" id="img_images_fig36.jpg"> +<figcaption> +<span class="smcap">Fig. 36</span><br> +<span class="small">A deep-sea Fish showing very elongated fins.</span> +</figcaption> +</figure> + +<p>Accompanying the loss of eyesight in deep-sea +animals we often find a very remarkable development +of organs, which may be regarded as +especially tactile in function.</p> + +<p>Many of the deep-sea Fish, for example, with +rudimentary eyes possess long barbels, and in +some cases the paired fins are enormously +<span class="pagenum" id="Page_140">[Pg 140]</span> +elongated to form delicate pointed organs like +the tentacles of a Polyp. Among the blind +Crustaceans, too, we often find enormously long +antennæ, and even the claws and legs are so +long and delicate that they bring to mind the +appendages of a Daddy-long-legs or a Harvest +spider.</p> + +<p>Just as a blind man acquires a remarkably +acute sense of touch, so, it seems, in the course +of generations, these blind animals of the abyss +have acquired extremely delicate tactile organs.</p> + +<p>The deep-sea Fauna is also remarkable for the +great number of animals which are phosphorescent. +As in the surface-swimming creatures the +phosphorescence is not confined to a few classes, +but probably occurs to a greater or less extent in +all the more important groups. The word “probably” +must be used in the previous sentence, +because it is not yet scientifically proved that +many forms which are supposed to be phosphorescent +are actually so; but the evidence is conclusive +that phosphorescence is a common and +widespread character of most of the deep-sea +Fauna.</p> + +<p>The Fish exhibit, perhaps more than any other +group, peculiar organs which are supposed, and +in many cases proved to be, used for the purpose +of generating light. In the <i>Stomiatidæ</i>, a +family of Fish related to the Salmons, there are +often numerous little organs, like minute bull’s-eye +lanterns, arranged in rows on the sides of the +body from the head to the tail, and in addition +to these in some species one or more pairs of +larger organs are seen on the upper lip just in +<span class="pagenum" id="Page_141">[Pg 141]</span> +front of or below the large eyes. It is not +certain what the colour of the light is that is +emitted by these organs, but it is very probable +that if the Fish could be seen in their natural +haunts they would have an extremely beautiful +effect.</p> + +<p>In describing the general characters of the +shallow water Fauna in Chapter II. reference +has been made to the remarkable lure at the end +of the tentacle of the Angler-fish. In the Angler +of the great depths this is also found, but in the +obscurity of their surroundings a lure, such as +that of the shore species, would be useless, and +it is actually replaced by an organ which is supposed +to be phosphorescent. The mouth is enormous +and armed with ferocious-looking teeth, the +body is rounded and adapted for burrowing in +the ooze, and we can well frame in our minds a +picture of the little Fishes and other creatures +attracted by the “will-o’-the-wisp” light, meeting +with a sudden death in the cavernous jaws of this +voracious deep-sea Fish.</p> + +<p>It is possible that in addition to the light given +off by definite organs, the slime secreted by the +skin either over the whole surface or certain circumscribed +regions, may be phosphorescent, but +how far this may serve as a means of illumination +must remain a matter of conjecture. The Crustaceans +are in some cases known to emit a phosphorescent +fluid. The naturalists of H.M.S. <i>Investigator</i> +found a brilliantly phosphorescent +liquid in the glands at the base of the antennæ +and elsewhere in certain deep-sea Shrimps, and +one of the Cray-fish from great depths is said +<span class="pagenum" id="Page_142">[Pg 142]</span> +to have two definite spots on the body that emit +a phosphorescent light.</p> + +<p>Several of the Star-fish and Brittle-stars from +the abyss are known to be brilliantly phosphorescent, +and there are some vivid accounts of the +light given off by Worms and various kinds of +deep-sea Polyps found in the dredge.</p> + +<p>It is possible that some of the more minute +forms of life that occur on the mud at the bottom +may also be phosphorescent. The <i>Phæodaria</i>, a +family of Radiolarians peculiar to deep water, +provided with thick heavy shells, have a curious +organ in their bodies which may be capable of +emitting light. If this is the case, it is not +unreasonable to suppose that the vast tracts on +the bed of the ocean may be faintly luminous +like the surface of the sea on a calm night.</p> + +<p>Among the other characters must be mentioned +a very prevalent deficiency in the salts +contained in the skeletons of these animals. +The skin of the Fish is usually soft and velvety +to the touch, the scales being either very thin and +few in number or altogether missing; the bones +are described as being so soft that it is easy to +pass a needle through them. The shells of the +Crustaceans, although frequently drawn out into +numerous long and pointed spines, are usually +deficient in carbonate of lime. The shells of +the Molluscs are, when compared with those that +live in shallower water, thin and brittle. The +Corals do not seem in this respect to show +much variation from their shallow water relations. +Some of the solitary forms seem to have +rather thinner shells, but the colonial genera +<span class="pagenum" id="Page_143">[Pg 143]</span> +have, as a rule, as good a support of carbonate +of lime in the abyss as elsewhere.</p> + +<p>Before proceeding to the next character, it is +necessary to digress a little to consider the food +of the animals in the abyss. In the absence of +any direct sunlight there can be no vegetable +growth, all of the animals must therefore be +carnivorous. The food must be either the living +bodies of the truly abysmal animals, or the +dead bodies of those that fall from the surface +waters.</p> + +<p>It is probable that the bodies of Fish and the +larger Invertebrates only rarely reach the bottom, +as they have to run the gauntlet of many different +forms of life living within 100 fathoms of +the surface. When, therefore, such a prize does +fall to the luck of a deep-sea Fish, it is important +that it should have accommodation for it before +the neighbours come to share the meal. This +may be the cause of the fact that deep-sea Fish +have, as a general rule, jaws and stomach that +are extravagantly large, even for a carnivorous +creature. The width of the gape and the extensibility +of the stomach reach their highest +grade in some of the deep-sea Eels, which have +been found containing Fish actually larger than +themselves. In these cases the stomach and +the body wall hang down from the under side +of the Eel’s body in the form of an enormous +membranous sac containing the prey.</p> + +<p>We have now considered very briefly some of +the principal modifications of structure exhibited +by the animals of the deep-sea, but before leaving +the subject altogether it is necessary to refer to +<span class="pagenum" id="Page_144">[Pg 144]</span> +a few of the more characteristic and remarkable +forms.</p> + +<p>Although it may be considered to be one of +the greatest scientific triumphs of the century to +have discovered the existence of animal life in a +region, which nearly all the distinguished men of +science of the last generation believed to be as +lifeless as the moon, the revelations of the dredge +brought with them a certain amount of disappointment.</p> + +<p>The study of the crust of the earth has revealed +to us the fact that in times long since gone +by, there existed not only the hairy Mammoths, +the Iguanodons, and many other terrestrial +monsters; but that the sea was peopled with +certain Reptiles, Fish, Molluscs, Echinoderms +and Crustaceans, which are now believed to be +extinct.</p> + +<p>When it was first discovered that some forms +of animal life had attached themselves to a telegraph +cable lying in 1200 fathoms, and that it +was therefore a fact that life existed in very +deep water, a successful application was made +by scientific men to the British Government to +assist them in a thorough survey of this hitherto +unknown field of investigation.</p> + +<p>The result of the voyages of H.M.S. <i>Lightning</i> +and H.M.S. <i>Porcupine</i> was to prove the +existence in water of 1000 fathoms in depth of a +rich Fauna of rare and very remarkable animals. +Among them were several new genera of Sea-lilies +and a very curious Heart-urchin. The Sea-lilies +that were then known to live in shallow +water were very few in number, and nearly all of +<span class="pagenum" id="Page_145">[Pg 145]</span> +them were free and unattached. Now, in past +times in the history of the earth different genera +and species of stalked Crinoids or Sea-lilies were +very plentiful, and from their abundance in +certain geological deposits, it is believed that +they lived in enormous numbers. The discovery +of the new genera of stalked Crinoids +in the abyss suggested that possibly there +might be found several other families of extinct +animals still surviving in the deep sea. +This view was supported by the Heart-urchin, +whose shell showed some striking peculiarities +that were only known in fossil genera.</p> + +<p>But the hopes that were felt, even if they were +not always expressed, were doomed to disappointment. +No living Ichthyosauruses or Plesiosauruses, +none of the remarkable Ganoid fish of +Devonian times, no Trilobites, no Cystoids nor +Blastoids,—in fact none of the most interesting of +the fossil types rewarded the investigators of the +<i>Challenger</i> and subsequent expeditions.</p> + +<p>It is perfectly clear to us now that, taken as a +whole, the deep-sea Fauna is not more ancient in +character than any other Fauna. It is true that +a few genera, such as those just referred to, have +survived, probably from very ancient times, without +much modification; but the vast majority of +forms are simply shallow water animals, which +have been profoundly modified in structure, and +adapted to the peculiar conditions of existence in +the great depths of the ocean. +<span class="pagenum" id="Page_146">[Pg 146]</span></p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_VII">CHAPTER VII. +<br><span class="medium">COMMENSALISM AND PARASITISM.</span></h2> +</div> + +<p>The term Symbiosis has been applied by naturalists +to the phenomenon of the living together +for mutual help or protection of different species +of animals or plants. It is a well-known fact, +to all those who have taken an interest in any +large group of animals, that some species are +nearly always associated with other species, belonging +perhaps to a different class altogether, +and very frequently mimicking them in form or +colour. At first it might be thought that most +of these cases could be dismissed as cases of parasitism; +but when the careful observer notices that +neither of the species is injured by the association, +the conditions of the partnership are evidently +very different to those of a blood-sucking +parasite and its ungracious host.</p> + +<p>Besides the words Symbiosis and Parasitism, +the terms Commensalism and Mutualism have +been applied to various cases of association of +different species of animals; but with the increase +of our knowledge of the habits of animals, it is +becoming more and more difficult to classify +all known cases under these four heads, and the +words are consequently often used with widely +different meanings.</p> + +<p>It will be perhaps the best plan to adopt in +this book, to avoid any attempt to give definitions +of these terms until a few cases illustrative +of each have been described.</p> + +<p>One of the commonest objects of the sea-shore +<span class="pagenum" id="Page_147">[Pg 147]</span> +is the Hermit-crab. From the open mouth of +what is apparently an empty shell a bundle of +claws and legs may be seen to protrude; turn +the shell over and it will scamper away into the +deeper parts of a rock pool. This is an association +of a living Crab with the shell of an animal that is +dead; but if the Hermit-crab be extracted it will +be seen that it has a soft and twisted tail, quite +unlike that of the shore Crabs, and that it could +not possibly live for any length of time without +the shelter and protection afforded by the +shell that it has appropriated to itself. The +Hermit-crab in the course of its life increases in +size, and when it gets too big for the shell it is +living in, it goes in search of another a little bit +larger and changes, until at last it attains to the +size and dignity that requires a full-grown Whelk +shell.</p> + +<p>In the waters of our coast just beyond the low +tide mark we often find that the shell containing +a Hermit-crab bears a Sea-anemone which belongs +to a species rarely found anywhere excepting +in association with a Hermit-crab. Moreover, +the Anemone is always seated in a definite +position on the shell, so that its mouth is turned +towards the jaws of the Hermit-crab when it is +extended, enabling it to catch any morsels of +food that escape the mouth of its comrade. +When the Hermit-crab has grown too large for +its shell, and moves into a new one, the Anemone +moves too, and takes up the same position on the +new shell that it occupied on the old one, and +the companionship is continued in this manner +throughout life. +<span class="pagenum" id="Page_148">[Pg 148]</span></p> + +<p>The advantage of this arrangement to the +Anemone is obvious, for it can not only obtain +its food after the manner of the other Anemones, +but it also gains a share of the food of the Hermit-crab. +The advantage to the Crab is not so apparent, +but it is probable that the Anemone, +being very distasteful to many Fish and other +animals, acts as a protector to it. The facts +that Hermit-crabs are extremely shy, darting +back into their shells when there is the +slightest sign of danger, and that they are extremely +good bait for many kinds of Fish, +suggest very forcibly that they have many +enemies among the inhabitants of the deep. +Any such covering as that afforded by the Anemone, +which hides to a great extent the character +of the shell, would be of protective value, but +when to that is added the fact that the Anemone, +which affords this covering, is avoided as uneatable +and distasteful by carnivorous Fish, there +can be no doubt whatever of the assistance that +it renders to the Crab in return for its board. +If any of my readers are sceptical about the +distastefulness of Sea-anemones I would ask +them to think of any instance in which Sea-anemones +are used for bait, and then to try the +experiment of offering pieces of them to the Fish +in an aquarium.</p> + +<p>An observation by Prof. Möbius in the Indian +Ocean affords another example of the use of Sea-anemones +in this respect. He discovered a little +Crab called <i>Melia tesselata</i> which carried about in +each of its claws a Sea-anemone. When the +Crab was alarmed it held them up in much the +<span class="pagenum" id="Page_149">[Pg 149]</span> +same way that a man holds a torch, as if it +would call attention to the fact that it had these +terrible weapons at hand. When the Anemones +were removed it carefully searched for them, +and held them up again when found, and even +when the Anemone was cut into pieces the Crab +diligently collected them, arranged them as far +as possible in their proper places, and held them +up together.</p> + +<figure class="figcenter illowp98" id="fig37" style="max-width: 25.125em;"> +<img alt="" class="w100" src="images/fig37.jpg" id="img_images_fig37.jpg"> +<figcaption> +<span class="smcap">Fig. 37</span><br> +<span class="small">Hermit-crab protruding from its hole in the sponge.</span> +</figcaption> +</figure> + +<p>But Sea-anemones are not the only animals +that seem to be generally distasteful to Fish. +Many of the Sponges are free from attack, and +could serve as a protection to the Hermit-crabs. +On our own coast a small brown Sponge +is not infrequently brought up in the dredge +surrounding and protecting a Hermit-crab; and +hidden somewhere in the substance of the sponge, +there may always be found a small shell which +lies at the end of the hole in which the Crab +lives. +<span class="pagenum" id="Page_150">[Pg 150]</span></p> + +<p>This association is, from the Crab’s point of +view, a more advantageous one than that with +the Sea-anemone, for it does away with the +necessity of any changes of shell, the Crab +and the Sponge growing up together. The +history of the companionship is probably as +follows:—A small Hermit-crab takes for its +shelter a small Gastropod shell, and upon this +shell a Sponge larva settles, grows and spreads, +until it surrounds the whole of it except the +hole from which the +Crab emerges. As +the Sponge grows +still further in thickness +the margin over-lapping +the aperture +of the shell expands, +leaving a conical +cavity leading from +the exterior to the +shell, surrounded, of +course, by Sponge +structure, in which +the Crab lives. +Thus as the Hermit-crab increases in size it is ever provided +with a wider hole to accommodate its body +by the growth of the Sponge, and the little shell +wholly deserted remains as a token of the past +history of the pair. But in the later stages of +growth a third creature is taken into the partnership, +in the person of a small segmented Worm +which lives in the hole with the Hermit-Crab. +The need for this third person seems to be one +of a sanitary character. The cleanliness of the +<span class="pagenum" id="Page_151">[Pg 151]</span> +Hermit-crab, which has no sponge to protect it, +is provided for by the simple expedient of frequent +changes into a new home. In this case it +is arranged for by taking into the home, on what +we may call board wages, an efficient scavenger.</p> + +<figure class="figcenter illowp83" id="fig38" style="max-width: 25.125em;"> +<img alt="" class="w100" src="images/fig38.jpg" id="img_images_fig38.jpg"> +<figcaption><span class="smcap">Fig. 38</span><br> +<span class="small">Section through a sponge (<i>D</i>) +showing <i>A</i>, the little shell; <i>B</i>, the worm; +<i>C</i>, the Hermit-crabs in their natural positions.</span> +</figcaption> +</figure> + +<p>In this remarkable association, then, no less +than four species belonging to four different +groups of animals are concerned. First of all +there is the <i>Gastropod</i> Mollusc, which forms a +shell for the <i>Crustacean</i> Hermit-crab to commence +life in, then there is the <i>Sponge</i> which protects, +and afterwards forms a shelter and home for the +Hermit-crab, and lastly, there is the <i>Annelid</i> +worm, which helps in its way to keep the house +clean in return for the scraps of food that fall +from the head partner’s table.</p> + +<p>A very similar association has recently been +described by Bouvier from the Gulf of Aden and +Red Sea waters. A number of simple solitary +Corals were thrown into an aquarium by a French +naturalist, some falling on their sides and some +on their crowns, but he noticed that, after the +lapse of some time, they were all in the erect +position again with their crowns of tentacles +expanded in the water. On carefully watching +them he observed that at the base of each Coral +there was a little hole from which emerged a +small unsegmented Worm, belonging to a family +that usually exhibits sand-burrowing propensities. +These Worms were found to be the agents which +restored the Corals to their erect positions. The +advantage of this arrangement to the Worm was +two-fold: it brought it into direct contact with +the sand in which it searches for its food, and, +<span class="pagenum" id="Page_152">[Pg 152]</span> +at the same time, it brought the Coral into such +a position as to hide and protect it from its +enemies above in a most effectual manner. To +the Coral it was obviously an advantage, in that +it placed it in a position to expand its tentacles +in search of the food it seeks in the water and +prevented a death from suffocation. A more +minute investigation of the Coral, however, +revealed the facts that hidden in its substance +there was a small Gastropod shell on which we +may suppose both the Coral larva and the Worm +settled when the partnership began, and that in +association with the Worm there was a small +bivalve Mollusc which probably acts as a +scavenger in the manner of the Worm in +the last mentioned case. Here again, then, +there are three different species living together +to their mutual advantage and commencing +their association on the shell of a fourth +species belonging to a different class of animals. +What words can we apply to these associations? +The Hermit-crab and the Anemone feed at “the +same table” and therefore they afford a case of +“Commensalism”; the Coral and the Worm are +of advantage to one another, the former in +shielding and protecting the latter and the latter +in keeping the former in an upright position, but +as they do not feed “at the same table” it is +not a case of “Commensalism” but rather one +of “Mutualism.”</p> + +<p>There are many cases, however, of the association +of animals in which, although the advantage +to one of the partners is clear, it is extremely difficult +to say what benefit is derived by the other. +<span class="pagenum" id="Page_153">[Pg 153]</span></p> + +<p>Living in a tube on our coasts is a very +common Worm called Sabella, and at the mouth +of the tube a little Polyp may frequently be +found which has received the fanciful name of +the “Household god of the Sabellids” (<i>Lar +Sabellarum</i>). The Polyp undoubtedly benefits +by the currents of water which the Worm sets +up when feeding, but it is difficult to see what +advantage, if any, the worm +gains from the presence of the +Polyp.</p> + +<p>Again, some of the Trepangs +are frequently inhabited by a +little Fish called <i>Fierasfer</i>, which +comes out from time to time to +feed and “take the air,” but +rapidly retreats into the body +of the Trepang on the slightest +alarm.</p> + +<figure class="figcenter illowp35" id="fig39" style="max-width: 11em;"> +<img alt="" class="w100" src="images/fig39.jpg" id="img_images_fig39.jpg"> +<figcaption><span class="smcap">Fig. 39</span><br> +<span class="small">A Trepang, or sea-cucumber.</span> +</figcaption> +</figure> + +<p>The large stinging Sea-anemones +of the Coral often afford +protection of a similar kind to +a little Fish. Saville Kent gives +a beautiful picture of a little +bright red Fish swimming about +on the disc of a large purple Sea-anemone, +and he says that it darts into the mouth when +alarmed. On our own coasts we may often +observe a number of little Fish generally belonging +to the Cod-family swimming round the disc +and tentacles of the large Jelly-fishes, and these, +when frightened, swim vigorously toward the +under surface of the umbrella and seek security +there. Sometimes as many as a hundred or +<span class="pagenum" id="Page_154">[Pg 154]</span> +more of them may be seen hovering round one +large Jelly-fish, and we can hardly estimate how +valuable to our sea fisheries is the protection +afforded by these great Medusæ to the young +Fish-fry. (<i>See Frontispiece.</i>)</p> + +<p>It was not my purpose in writing this book to +point out the practical value of scientific investigation, +but this history of the Jelly-fish and +Codling cannot be passed without comment. The +Jelly-fish might readily be regarded by the +ignorant not only as useless to man, but, in so +far as they sometimes choke his fishing nets and +sting his hands and arms, a positive nuisance to +him. Scientific investigation when pursued by +properly qualified persons for its own sake, and +not for any definite commercial results that may +possibly come out of it, frequently reveals facts +of the utmost importance, such as the one that +has just been mentioned.</p> + +<p>There are some other cases of association +which would on first consideration be called +undoubtedly cases of parasitism, but as this +term has been used somewhat vaguely in popular +English, it would be well, before proceeding +further, to place before the reader a definite +statement of the sense in which the word is +used in this book.</p> + +<p>In many of the cases that we have mentioned +hitherto of animals living together, no apparent +injury is inflicted upon either of the associates, +but a very definite and decided advantage +accrues to each of them, by the association.</p> + +<p>In other cases, however, whilst no apparent +injury is inflicted on either, the advantage +<span class="pagenum" id="Page_155">[Pg 155]</span> +of the partnership falls entirely to one of +them.</p> + +<p>In a third set of cases one of the associates +feeds upon the blood or tissues of the other +without rendering it any service in return, and +consequently inflicts either temporary or permanent +injury. These are cases of parasitism. +In such an association the animal that inflicts +the injury is called the “parasite,” and the one +that receives it, the “host.”</p> + +<p>One difficulty the naturalist has to contend +with in trying to use these terms correctly is +that of finding out whether in any particular case +an injury is inflicted or not; another is that of +determining whether those animals should be +called parasites which injure, alter, or destroy +the tissues of their hosts without feeding upon +them.</p> + +<p>A few cases will throw more light upon the +subject than any further discussion of the difficulties +surrounding the application of these +terms.</p> + +<p>One of the commonest Corals to be found +upon the coral-reefs of both the Old and New +world is one called <i>Millepora</i>. In the Millepores +of the Pacific region we very frequently +find a number of Barnacles (called <i>Pyrgoma +milleporæ</i>) so deeply buried in the substance of +the Coral that their presence is indicated only by a +small oval hole on the surface. There can be little +doubt that in the course of the growth of these +Barnacles they distort, if they do not actually +destroy, some of the connecting canals of the +Coral in their immediate neighbourhood, but +<span class="pagenum" id="Page_156">[Pg 156]</span> +their food is derived entirely from the water +that surrounds the Coral and not any portion +of it from the cells or tissues of the Coral-polyps +themselves.</p> + +<p>There is a great deal of difference in the +Millepores from one and the same coral-reef, +in the extent to which the Barnacles have +attacked them. In some specimens large areas +of the Coral are beset with the little holes, in +others only one or two may be found on the +whole colony, whilst others again are quite free +from them. Now when we compare carefully +the anatomy of those Millepores with the +Barnacles and those without them, no single +sign or symptom can be found that the vigour +or strength of the former is in any way impaired. +If then there is no evidence that the +Barnacles are parasitic, in the sense that they +are injurious to the Millepores, we must next +inquire whether they could possibly be of any +service to them.</p> + +<p>The polyps of the Millepores feed after the +manner of the polyps of other Corals, upon +minute organisms floating in the sea; these they +paralyse and capture by means of tentacles bearing +stinging cells. The food is in the ordinary +course brought within reach of the tentacles +by the tides that sweep over the reefs. The +Barnacles also feed upon minute organisms of +the same kind, but they are provided with six +pairs of long feathery legs which by a curious +vibratory movement create currents in the water. +When there are many Barnacles in close proximity +to one another it is quite probable that the +<span class="pagenum" id="Page_157">[Pg 157]</span> +water is considerably disturbed by these currents, +and the constant and rapid flow of fresh water +bearing food-organisms benefits, not only the +Barnacles, but also the Millepore polyps in their +neighbourhood.</p> + +<p>Thus the Barnacles <i>may</i> be a benefit to the +Millepores in which they live. It cannot be +asserted, however, that this probability is a +proved fact. A great deal more knowledge +about the rate of growth of the Corals which +are and are not affected, must be acquired +before such an assertion could be made: but the +<i>probability</i> that the Barnacles may be of service is +sufficient to cause us to hesitate before branding +them with the epithet of “parasites.”</p> + +<p>This particular case, which has been given +above in some detail, may be regarded, in a +sense, as a test case, because other animals +besides the Barnacles, which gain their food by +producing currents, are found in Corals. Such +are the tubicolous Worms, bivalve Molluscs, and +certain Sponges. So plentiful are these on the +older branches of some Corals, that quite a rich +Fauna belonging to several groups of animals +may be found by carefully studying them. +These might all be dismissed as parasites by +the non-inquisitive mind, but many of them, at +any rate, may be regarded by the more cautious +naturalist as not injurious, and others perhaps as +positively beneficial to the Coral on which they +live. There is a very curious case of symbiosis +mentioned by Semper, which may be related +here as similar in some respects to those above +quoted.<span class="pagenum" id="Page_158">[Pg 158]</span></p> + +<figure class="figcenter illowp56" id="fig40" style="max-width: 16.9375em;"> +<img alt="" class="w100" src="images/fig40.jpg" id="img_images_fig40.jpg"> +<figcaption><span class="smcap">Fig. 40</span><br> +<span class="small">A Crab-gall on a branch of a Seriatopora.</span> +</figcaption> +</figure> + +<p>On the shores of the Philippine Islands and +in other parts of the Pacific Ocean there is a very +common coral named <i>Seriatopora</i>. It is composed +of numerous delicate branches, terminating +in fine pointed extremities, forming hemispherical +shrub-like masses, six or eight inches +in diameter. Semper noticed that on some of +the branches of these Corals there were little +heart-shaped swellings, +which had the appearance +of malformations or +structures corresponding +to the galls on the leaves +and branches of trees. +Each of these swellings +contained a cavity, communicating +with the exterior +by two minute +holes, in which there +was imprisoned a small +Crab.</p> + +<p>By the examination +of a large number of +specimens, Semper came +to the conclusion that +the history of these structures was somewhat as +follows. The young Crab, when it settled down +on the branch, produced an irritation which in +some way caused a gall-like growth of the tissues of +the Coral. This growth continued until it formed +at first a case or sheath for the protection of the +Crab, and eventually, as the Crab increased in size, +a cage from which it could not do more than +protrude its tentacles and claws when feeding. +<span class="pagenum" id="Page_159">[Pg 159]</span></p> + +<p>It seems very improbable that these cage-like +swellings upon the branch can be of any great +disadvantage to the Coral. It is true that they +destroy the beautiful symmetry of the branch, +and give it a distorted and diseased appearance; +but this is only an æsthetic disadvantage, which +does not probably count for much in the struggle +for existence on the Coral-reef. To the Crab the +arrangement is undoubtedly an advantage, as it +gives it a secure position, free from the attack of +its ordinary foes, where food is probably abundant +and easily obtained.</p> + +<p>The skin of Whales is often beset with Barnacles; +in fact some species of them are found +nowhere else but on these Mammals. They are +usually deeply embedded in the skin, only a +small round hole through which the legs can +be protruded, communicating with the exterior. +These Barnacles do not feed upon the tissues and +juices of the Whale, but, in the usual manner of +the non-parasitic Barnacles, upon organisms that +swim freely in the water. The advantage to the +Barnacles is obvious, as the movements of the +Whale through the water must bring them in +reach of constant fresh supplies of food, but the +benefit to the Whale is not so clear. It cannot +be supposed for a moment that the Barnacles +assist the Whales in their search for food, nor can +they be regarded, when present in great numbers, +as a protection to the skin by the strength +afforded by their thick calcareous shells; at the +same time there is no reason to suppose that +their presence is an inconvenience or in any way +harmful to the Whales. +<span class="pagenum" id="Page_160">[Pg 160]</span></p> + +<p>These cases of animals bearing on their bodies +other creatures which are not in the strictest +sense of the word parasites, are but instances of +a phenomenon that is very widely spread among +marine organisms. There are many cases, however, +in which plants and inorganic foreign bodies +play a very important part in the economy of +animals.</p> + +<p>In our chapter on the free-swimming organisms +of the ocean, mention has been made of the delicate +and beautiful creatures called Radiolarians. +Many years ago it was discovered that each of +these animals bears in its protoplasm a number +of little cells, which from their colour received +the name of “the yellow cells.” It was clear +from observation and experiment that they were +neither organs nor products of the Radiolarian, +but independent organisms belonging to the +Vegetable Kingdom.</p> + +<p>More recently cells similar to these have been +found in many of the Corals, in Worms, and +other animals, and there can be no doubt now +that when present they perform very important +physiological functions which materially assist +their host in its growth and development.</p> + +<p>So numerous are these “yellow cells” in some +Polyps and so important must be their influence +on their vital processes, that it may be confidently +asserted that the Polyps could not continue to +exist for long without them. In the genus <i>Millepora</i>, +for example, no single specimen and no single +fragment of a specimen that I have examined +was devoid of them; and although the numbers +vary considerably the most superficial canals +<span class="pagenum" id="Page_161">[Pg 161]</span> +of this Coral may in all cases be described as +crowded with “yellow cells.” But as the +“yellow cells” are certainly of great physiological +importance to the Millepore, it is equally +certain that the secretions and the protection +afforded by the Millepore are of extreme importance +to the “yellow cells.” In fact it is not +going too far to say that the Millepore and its +“yellow cells” are dependent upon one another +for their existence, and the naturalist might say +with a great deal of truth that this particular +Coral is not, strictly speaking, animal in nature, +but rather an animal and vegetable combination.</p> + +<p>Many years ago there was a bitter controversy +among learned men on the question of the animal +or vegetable nature of Corals. The great naturalist +Linnæus, who was appealed to for his support +by both parties to the controversy, took up +a middle position, asserting that they were partly +of the nature of animals and partly of the nature +of plants, and hence the term “zoophytes,” <i>i.e.</i> +animal-plants, came to be applied to them. There +can be no doubt that in the end the position in +the controversy, assumed by Linnæus, became +untenable, and the supporters of the animal view +of zoophytes won all along the line. It is curious, +therefore, that we are now in a position, not to +support the view of Linnæus, but to assert that +some Corals are essentially a combination of animals +and plants.</p> + +<p>Plants are of use to marine animals, however, +in another manner. Mention has already been +made of the way in which many animals resembling +in colour, and even in form, certain kinds of +<span class="pagenum" id="Page_162">[Pg 162]</span> +sea-weeds, escape the attention of their enemies +and hide for safety among the plants they simulate. +Sometimes, however, the weeds will grow +upon the shells of the animals, and thus hide +them even more effectually. One of the most +remarkable instances occurs in a Spider-crab that +is common upon our own coasts. The <i>Inachus</i>, as +it is called, is usually covered with a little forest +of algæ, which do not grow there naturally, but +are actually placed on the carapace by the Crab +itself. If the plants be scraped off artificially the +Crab will go in search of fresh ones, carefully +chew the bases until they are soft, and then +deliberately decorate the carapace with them as +before.</p> + +<p>There are some Molluscs that artificially decorate +themselves with little shells and other objects +in such a manner as to completely hide their +general form. One of the most remarkable +instances of this occurs in the Gastropod <i>Xenophora</i>, +which covers its own shell with numbers +of others belonging to a smaller species, so that +in the natural state it has the appearance of a +conglomerate of shells. The manner in which the +smaller shells are fixed has not yet been described, +but from the orderly arrangement which they +exhibit in some cases there can be little doubt +that they are deliberately placed in position by +the Gastropod itself and not attached by accidental +contact.</p> + +<p>In both these cases it is clear that the reason +for the phenomena described is that of affording +a covering or mantle, which hides or obscures the +real form and character of the living animals. +<span class="pagenum" id="Page_163">[Pg 163]</span></p> + +<p>Many of the Worms use little bits of shell and +grains of sand to build up a tube for the protection +of their bodies. One of these—the <i>Terebella</i>—is +very common on our shores, the sandy +tubes ending in a tuft of fine filaments, and +decorated all over with tiny little stones or +shells, projecting an inch or two from the surface +of the sand. In some localities these tubes +may be found in thousands when the tide is +low.</p> + +<p>Another form—<i>Pectinaria</i>—constructs much +firmer tubes, which retain their cylindrical shape +after the death of the animal. In the process of +construction this Worm must carefully select the +grains of sand, for when the tube is examined +with a magnifying glass the particles will be +seen to be of almost exactly the same size, and +arranged in their places with a mathematical +precision.</p> + +<p>But Worms are not by any means the only +animals that use the sand in this manner for the +protection of their bodies. There are some +kinds of Polyps, belonging to the family <i>Zonathidæ</i>, +a peculiar group of Sea-anemones, in +which the body-wall is considerably strengthened +by foreign bodies of various kinds. The <i>Zoanthus</i> +does not, like the Terebella-worm, form a +tube or case in which the body can freely move +up or down, but sticks the grains of sand into +its skin, so that they become in the older forms +deeply buried in the tissues and give a considerable +support to the body-wall.</p> + +<p>The <i>Cerianthus</i>—another Sea-anemone—forms +a tube which is partly composed of a matted +<span class="pagenum" id="Page_164">[Pg 164]</span> +network of stinging threads, and partly of the +mud in which the animal lives.</p> + +<p>The use of foreign inorganic substances for the +protection or concealment of animals is not, +strictly speaking, however, a part of the subject-matter +of this chapter, which was intended for the +consideration of the associations of two different +kinds of living organisms.</p> + +<p>The subject of Parasitism must now be considered, +a subject which presents so many +features of interest that it is possible here only +to touch on a few points of general importance. +It is a well-known truism to say that Parasitism, +whether in human society or in animal life, leads +to degeneration; but there are degrees of parasitism +among animals, and consequently degrees +of degeneration exhibited by animal parasites. +We may roughly divide them into two classes, +the outside or skin parasites and the internal +parasites, the latter being invariably far more +modified in structure and in development than +the former.</p> + +<p>Among the terrestrial animals we find a great +number of external parasites, such as the Fleas +and the Bugs, which are only slightly modified, +as in the loss of their wings, owing to their +habits, and can live an active, if not a very +prosperous, life for some length of time apart +from the society of their hosts. There are +others, such as the Mosquitoes, Ticks, and +Leeches, which are only occasional parasites; +that is to say, they will suck the blood of +another animal when the opportunity is presented, +but failing that, are able to continue +<span class="pagenum" id="Page_165">[Pg 165]</span> +their life and their race independently. It is +not surprising, however, that the terrestrial +Vertebrates should be thus subjected to the +attacks of these parasites, as their feathery or +hairy skin affords a shelter and a foothold, from +which the efforts of their hosts to dislodge them +are exercised in vain.</p> + +<p>The skin of Fish, although covered with over-lapping +scales, is smooth and slippery, and with +the rapid movement through the water many of +the forms of parasites of the types we meet on +land would, if they existed in the sea at all, +find a difficulty in securing an attachment. It +is, however, provided with another means of +defence against skin parasites, in the possession +of numerous mucous glands which keep the body +bathed with a slimy fluid.</p> + +<p>Everyone must have noticed the slime that +exudes from freshly killed Fish, and if the finger +be pressed along the skin it is possible to see the +openings of the glands as the slime is squeezed +out. In the majority of Fish the openings of +the glands are most easily seen on the jaws and +the flap of the gill cover.</p> + +<p>We must remember that the sea is in most +places teeming with the larvæ of Worms, Barnacles +and Zoophytes, and the spores of Algæ and +Fungi of various kinds. Logs of wood, the iron +supports of piers, and the bottoms of ships become +covered with various fixed forms of animal and +vegetable life when submerged in the sea-water +for even a few weeks. How is it, then, that the +bodies of the Fish are usually so clean and wholesome? +The answer to this question is probably +<span class="pagenum" id="Page_166">[Pg 166]</span> +to be found in the slime which, passing continuously +over the skin, removes the larvæ and the +spores before they can secure a firm attachment.</p> + +<p>The Crabs, Lobsters and other Crustaceans +free themselves from their skin parasites at every +moult, but in some of the large, old Lobsters and +Crabs that are caught a considerable number of +Worms, Barnacles and weeds are frequently found +firmly-fixed to the carapace and claws. The +Limpets and Winkles of our rock pools are often +covered with a little forest of Algæ.</p> + +<p>The shells of other Molluscs are, however, kept +remarkably clean, and the method by which they +destroy the spores, etc. that settle upon them is +not yet fully understood.</p> + +<p>One of the most serious of the external parasites +is the Hag-fish. This remarkable animal is +eel-like in shape, although very different indeed, +anatomically, from all the true Fishes, and buries +its head in the skin of the Cod and other Fishes +as it feeds upon their flesh. In some cases the +whole body of the Hag gets inside the host, and +it thus becomes an internal parasite. It causes +an immense destruction of valuable food fish in +some districts.</p> + +<p>Closely related to the Hag is the marine +Lamprey, which fastens itself to Salmon by its +suctorial mouth, causing considerable wounds. +This parasite sometimes reaches to a length of +two feet, and is often carried many miles up +the river by the host to which it is attached.</p> + +<p>Most of the Leeches occur either in fresh water +or in damp forests and marshy places. There is +one, however, named <i>Pontobdella</i>, which is found +<span class="pagenum" id="Page_167">[Pg 167]</span> +only in sea-water. It is difficult to give an exact +statement as to its size, because, like all its relations, +it is capable of very extensive movements +of expansion and contraction, but the <i>Pontobdella</i> +is large for a Leech, and when moderately contracted +it may be two or three inches in length. +The body of this Leech is covered with small +tubercles, and it has a large round sucker at +each end. Its favourite hosts are the Sharks +and Rays, but as it usually drops back into the +water when these Fish are hoisted on to the deck +it is not very commonly seen in the fishermen’s +boats.</p> + +<p>The most common external parasites of Fish +are the Fish-lice. Most of these are little Crustaceans, +belonging to a group which includes the +Wood-louse. They have curiously flattened +bodies, provided with short, bent legs, terminating +in sharp hooks, by which they adhere to +the body of the Fish and crawl about over the +skin. Some of these parasites seem to prefer the +tongue as a resting-place, the genus <i>Glossobius</i>, +for example, being found in this position on the +Flying-fish of both the Pacific and Atlantic Oceans. +In <i>Glossobius</i> we find a very remarkable difference +in size and form between the males and females, +a condition of affairs which is of very common +occurrence among the parasitic Crustaceans. The +male in this particular case is so small that it is +entirely concealed beneath the tail of the female. +In another genus a still more interesting condition +has been observed, the small young forms +which are males growing up, and changing in +later life into females. +<span class="pagenum" id="Page_168">[Pg 168]</span></p> + +<p>There is a remarkable parasite called <i>Sacculina</i> +which may sometimes be found on the under side +of the tail in Crabs. In shape it is like a small +pea or bean, and is attached to its host by a +number of root-like processes, which penetrate +through the skin and burrow deeply into the +subjacent tissues. It would be quite impossible +to tell to what group of animals this parasite +belongs by the study of the adult form alone. +It is, in fact, little more than a skin full of eggs. +When the development of the eggs is watched, +however, it is observed that the young <i>Sacculina</i> +as it is hatched is very much like the Nauplius +larva of a Barnacle. The later stages of the +development prove that whatever may happen +to the adult the <i>Sacculina</i> must be related to the +group of the Cirripedia. Later on it is found +that the females settle down on a Crab, lose all +their limbs and other Cirripedian characters, and +finally degenerate into a mere palpitating sac of +eggs.</p> + +<p>The males never pass beyond the second stage +of development known as the Cypris stage. +Several of them may usually be found attached +to the female, and although they always remain +extremely minute they do not lose entirely their +Crustacean features.</p> + +<p>For those who are in search of parasites, however, +there is no more fruitful ground than the +gills. That these organs should be a good place +for attack is not surprising, when we consider +that to maintain the respiration of the animal a +constant flow of sea-water over them must be +kept up, and this must bring with it many larval +<span class="pagenum" id="Page_169">[Pg 169]</span> +forms which may take the opportunity to attach +themselves as they pass through the meshes of +the gill filaments. Moreover, it is in the gills +particularly that the blood current comes into +closest contact with the water, and it requires +but a little puncture on the part of the young +parasite to reach a constant supply of this nourishing +fluid.</p> + +<p>It is in the gill-chambers that we find most +frequently representatives of that interesting +group of animals, the parasitic Copepods.</p> + +<figure class="figcenter illowp30" id="fig41" style="max-width: 7em;"> +<img alt="" class="w100" src="images/fig41.jpg" id="img_images_fig41.jpg"> +<figcaption><span class="smcap">Fig. 41</span><br> +<span class="small">A parasitic Copepod.</span> +</figcaption> +</figure> + +<p>It would be difficult to recognise +them as Copepods if we were to +judge by their adult characters alone. +Unlike the brisk, brightly-coloured +creatures with long rowing antennæ +that we have described above as +living a free life in the surface waters +of the ocean, these parasites have a +white sac-like body, with short blunt +processes representing the legs, no +eye, and generally two long thread-like +bags of eggs attached to the sides +of the rudimentary tail. As we found in the +case of the <i>Sacculina</i>, the true zoological position +of these parasites can only be determined by +reference to their developmental history.</p> + +<p>In the gill-chamber of the Prawns we find a +very much modified parasite, which is closely +allied to those skin parasites of Fishes mentioned +above. Many of my readers may have noticed +that in some Prawns there is a wart-like swelling +on one side of the neck. If the skin be removed +<span class="pagenum" id="Page_170">[Pg 170]</span> +it will be observed that this is in reality a cup-shaped +protrusion on the wall of the gill-chamber +covering a little, flat, soft animal. In past times it +was thought that this was a young flat fish, and +a wonderful story of its development was fabricated +on the strength of this error. It is now +known to be one of these extremely degenerate +Isopod parasites called <i>Bopyrus</i>.</p> + +<p>It is a curious fact that there is very rarely +indeed more than one of these parasites on a +single Prawn. If there is one in the right gill-chamber +there are none in the left, and <i>vice versâ</i>. +It is difficult to find a satisfactory explanation +for this, for it is not at all probable that, during +the lives of the many hundreds of Prawns that +have been examined, only one larva has passed +through the gill-chamber of each individual. The +explanation must be looked for in some hitherto +unknown influence which the parasite has upon +the constitution of the host, rendering it unsuitable +for the attachment of another <i>Bopyrus</i> of the +same habits. The case is by no means unique. +There are several instances of Fish and other +animals that bear one, and never more than one, +parasite of a particular species.</p> + +<p>A few words must now be added about the +internal parasites of marine animals. The subject +is really an immensely wide one; for the +intestines, body cavities, and even blood-vessels +of Fish are liable to the attacks of many different +forms of Flukes, Tape-worms, and other kinds of +parasites which are not even known by name, +perhaps fortunately, to the general public.</p> + +<p>The life-history of some Flukes that occur in +<span class="pagenum" id="Page_171">[Pg 171]</span> +terrestrial animals has been satisfactorily worked +out, and we know that, in most cases, they must +infest two different hosts before they can reach +maturity. The first of these hosts is usually an +Invertebrate, and the second a Vertebrate animal. +Moreover, it is known that the larvæ are +extremely particular in their choice of the first +host, attacking one species, and one species only, +of Snail or Slug, or whatever Invertebrate its +first host may be. If the first host dies a natural +death or is swallowed by any other animal than +the parasite’s proper second host, it—that is to +say, the parasite—dies. It seems probable that +the Flukes that infest the intestines of marine +animals pass through some similar life-history, +but owing to the great difficulties that confront +the observer their development has not yet been +thoroughly investigated. Similarly the life-histories +of the Tape-worms, with which a very +large number of marine animals are infested, +are not yet known to us. It is comforting to +know, after looking through the volumes of +papers on these internal parasites of marine +animals, that none of them have been shown to +be, even occasionally, parasitic upon man, and +we can continue our Fish diet without any misgivings +on that score. An exception must, however, +be made to this statement for the semi-marine +Salmon and Sturgeon, which are suspected +of being the first hosts of a human Tape-worm.</p> + +<p>It is perhaps unsatisfactory to dismiss the +internal parasites of marine animals with so +few words, but I feel compelled to do so, not +only because I have nearly outrun the limits +<span class="pagenum" id="Page_172">[Pg 172]</span> +of space, but because we possess so little positive +information on the subject, which is of +greatest interest to us here, of their developmental +history. Lists of species infesting different +Fish and Whales could be published, a statement +of the points of anatomical importance +which distinguish the families could be written, +but they would present few features of interest +to the general reader.</p> + +<p>It may be well to point out before the chapter +is closed, however, that there is probably no +branch of our subject that is so little known +and presents such a wide and important field for +future investigation as the life-histories of these +marine parasites.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<h2 class="nobreak" id="CHAPTER_VIII">CHAPTER VIII. +<br><span class="medium">THE ORIGIN OF THE MARINE FAUNA.</span></h2> +</div> + +<p>When we survey the distribution of living +organisms over the surface of the globe, we +cannot fail to be impressed with the enormous +range in the characters of the physical conditions +which are capable of supporting animal and +vegetable life. Thus we find Birds flying in the +sunlight of the cold and very light atmosphere of +the mountain tops, and Fishes swimming in the +chill darkness of the depths of the ocean, supporting +a pressure of two tons to every square +inch of their bodies. We find Algæ, which give +the snow sometimes the name of “Red snow,” +flourishing at temperatures below the freezing +<span class="pagenum" id="Page_173">[Pg 173]</span> +point of water, and we meet with Insect larvæ +swimming freely in the water of the hot springs. +Some sea-water animals can only be induced to +live in the aquarium when the water is kept as +pure as it is in the open sea, and languish and +die as soon as any impurity occurs; on the other +hand, several of the Crustaceans seem to flourish +best in stinking and putrescent pools. The +desert, the forest, the swamp, the lake, the +river, as well as the surface and the bottom +of the sea have each their characteristic set of +animals and plants modified in structure and +form to support life in their natural habitats.</p> + +<p>There can be no doubt that at the time when +animals and plants first made their appearance +upon the earth, their distribution was far more +limited than it is now, and that all the adaptations +to life in special and extraordinary conditions +have been acquired in the course of +evolution by organisms which originally existed +in one particular zone of the earth.</p> + +<p>The reasons which have led scientific men to +this opinion are manifold, but not the least important +of them are those based upon the presence +of organs or rudiments of organs of animals +of the present time, which could only have been +called into existence at a period when their +ancestors had an altogether different habit of +life.</p> + +<p>For example, in the Birds and Reptiles, as +well as in the Mammals, the presence of openings +in the throat during the early stages of development, +similar in their position, in their blood-vessels +and in other respects to the openings of +<span class="pagenum" id="Page_174">[Pg 174]</span> +the gills in Fishes, indicates that their ancestors +in remote periods lived in water and not on dry +land.</p> + +<p>Again the presence of rudimentary eyes in the +Mole and other subterranean animals indicates +that at one time its ancestors must have lived in +the light of the day. The characters of the +embryos of some of the land and fresh water +Snails proves that they are derived from ancestors +that lived in the sea.</p> + +<p>When we collect together all the evidence of +this kind and place it side by side with the facts +revealed to us by Geology, the irresistible conclusion +is arrived at that all animals are originally +derived from ancestors that lived in the sea. +And when we consult the botanists and find +that they are agreed that all plants must have +had a marine origin also, the case for the sea +being the original home of living organisms may +be said to be completed.</p> + +<p>It is difficult to picture to ourselves the condition +of the earth in those very distant times, +when the dry land bore no forests nor grass, the +air supported no Birds nor Butterflies, and in the +rivers and lakes swam no Fish nor Frogs. It +must have been “dry” land indeed, when there +were no trees to attract the rain clouds and no +herbs or mosses to retain the moisture on the +ground. The rivers must have risen and fallen +with great rapidity as they carried away the +rain that fell in cloud-bursts on the mountain +tops.</p> + +<p>But speculation on the character of the land in +those times is not within the scope of this work, +<span class="pagenum" id="Page_175">[Pg 175]</span> +and we must turn again to the sea to inquire +where the primordial animals and plants lived in +the days of a lifeless land.</p> + +<p>We have seen that in the sea there are three +possible habitats for animals and two for plants. +The surface waters of the great oceans bear a +characteristic population of animals and plants, +the bottom of the sea supports a considerable +number of animals but no plants, and lastly +the shallow waters exhibit an immense variety +of Sea-weeds, Fish, Worms, and other creatures. +Which of these three was the original cradle of +the great classes of animals and plants?</p> + +<p>The early discovery of certain animals in very +deep water which are closely allied to, if not +identical with, some fossils of early geological +strata, suggested the idea that a very primordial +set of creatures might be found at the bottom of +the sea when it was more thoroughly investigated; +but as I have pointed out in a previous +chapter the hopes of those who anticipated the +discovery of a rich Fauna of “living fossils” were +doomed to disappointment.</p> + +<p>It is not probable, however, that the abyss of +the oceans could have been the cradle of life, +even if it had shown a more ancient Fauna than +it actually does.</p> + +<p>We cannot tell in what form life first appeared +upon the earth. Whether the unstable living +substance called Protoplasm was in the earliest +conditions of the globe formed spontaneously +by the chance combination of its elements, or +whether some germ or other made a hazardous +journey through space from another planet enwrapped +<span class="pagenum" id="Page_176">[Pg 176]</span> +in the casing of a meteorite, are +questions upon which no light has yet been +thrown by scientific observation or speculation; +but this can be said, that at a very early period in +the history of life upon the earth the simple +green plants must have played an important +part. It is on the substances that are formed +by the activity of this green coloured substance +that all plants and animals are directly or indirectly +dependent for their food in the present-day +economy of Nature, and we are forced to +believe that, whatever may have been the form +of the earliest living things, Chlorophyll—the +green coloured substance of plants—must have +had an extremely ancient origin.</p> + +<p>Now, in the darkness of the ocean depths +Chlorophyll does not and cannot exist; for it +is one of its characteristic features that it is +active only in the rays of direct sunlight; and, +therefore, it is extremely improbable that the +cradle of the marine Fauna could have been +there. We are then left with two alternatives. +It must have been either at the bottom of the +shallow waters or on the surface of the seas.</p> + +<p>Both of these sites have had their advocates, +but the balance of opinion has now turned +decidedly in favour of the first of them—the +shallow waters. It is not easy to explain the +reasons for this view without assuming a fairly +complete knowledge on the part of the reader of +the various forms of life that are found in the +sea, but still a few words of explanation may be +written to indicate that the view is a reasonable +one. +<span class="pagenum" id="Page_177">[Pg 177]</span></p> + +<p>In the first place we find, when we take +a general survey of the animals that live in the +surface water, that they are all specially modified +in some way or another in structure or development +in adaptation to the peculiar conditions of +their life. The long spines of the Foraminifers +and the Crustacean larvæ, the air-bladders of +the Portuguese men-of-war, the oil drops of +the Copepods, the raft of the Mollusc <i>Janthina</i> +are, as we have seen, among the characters which +distinguish this peculiar Fauna. Now, when we +compare these surface-dwelling forms with their +nearest relations in the shallow waters, the conclusion +we come to is that these features have +been acquired by the ancestors of the former, +which may have been similar in some respects to +those now living in shallow water.</p> + +<p>Some of the Gastropods of the shore-waters +have a simple cup-shaped shell like that of the +common Limpet, but the great majority of them +have a shell that is twisted up into a spiral +form. This twisting of the shell is, of course, +due to the twisting of the mantle or fold of skin +which secretes the calcium carbonate of which +the shell is mainly composed; and, when we +study the internal anatomy of the animal we +find that the shape of the mantle is associated +with a loss of the organs of one side of the body. +To put a long story into a few words, we may +say that the Gastropods with twisted shells are +lop-sided. Now when we examine the shells of +the Gastropods that live in the surface waters of +the ocean we notice that their shells are (with +a few exceptions such as <i>Janthina</i>) perfectly +<span class="pagenum" id="Page_178">[Pg 178]</span> +symmetrical, and we might jump to the conclusion +that this was due to a corresponding +symmetry of the internal organs.</p> + +<p>Such a conclusion would, however, be an +erroneous one, for the results of the careful +anatomical study of these Molluscs proves most +definitely, that although a false symmetry of the +organs is often shown, there is a general suppression +of the organs of one side of the body. +A study of the development of these animals +also shows, that in the early stages of their life, +the shell is not symmetrical like that of the +adult, but twisted into a spiral like that of a +Whelk or a Periwinkle. These facts indicate +that the surface-swimming Molluscs have passed +through a stage in their evolution when their +bodies were twisted up into a spiral shell, and +that the false symmetry, which they exhibit +in the adult condition, is an adaptation to their +peculiar habits of life. The study of the group +of Gastropods alone then does not give us any +evidence in favour of the view that the surface-swimming +Fauna is primitive; in fact, it proves +almost conclusively that its share in the Fauna +has been contributed from the shallow water +districts.</p> + +<p>The group of the Tunicates affords similar +evidence. There is no good reason for believing +that the Salps and <i>Pyrosoma</i> which drift about +in the surface waters are more primitive than +the fixed Sea-squirts of the rocks and Sea-weeds, +in fact, the view is gaining ground, as our +knowledge increases, that all the free Tunicates +must have passed through a sessile ancestry. +<span class="pagenum" id="Page_179">[Pg 179]</span> +The evidence afforded by the Cœlenterates is +not so potent. Several naturalists believe that +some free-swimming form of Jelly-fish was the +ancestor, and that the fixed Zoophyte was a +stage introduced into the life-history at a later +period in the evolution of the group. Others +believe that the Zoophyte-stage came first and +that the Jelly-fish was introduced, for the +purpose of distributing, over a wide area, the +eggs of the species. My own researches lead +me to incline towards the latter view, but I feel +that it is still far from being proved.</p> + +<p>A great deal more could be written upon this +fascinating speculation about the origin of Life +in the Sea. But it is still a speculation, and +all that can be done at present is to weigh the +evidence carefully and see in which way the +scale seems to point. If I have succeeded in +making clear to the general reader the nature +of the evidence we can use in judging this +question, and have indicated to him the direction +in which it seems to <i>me</i> to point, my task has +been accomplished.</p> + + +<hr class="chap x-ebookmaker-drop"> + +<p><span class="pagenum" id="Page_180">[Pg 180]</span></p> +<div class="chapter"> +<h2 class="nobreak" id="INDEX">INDEX.</h2> +</div> + +<ul class='index'> + +<li class='ifirst'>A.</li> + +<li class='indx'>Air-bladders in Plankton, <a href="#Page_90">90</a>.</li> + +<li class='indx'>Alcyonarians of Coral-reef, <a href="#Page_67">67</a>.</li> + +<li class='indx'>Alcyonium, <a href="#Page_42">42</a>.</li> + +<li class='indx'>Alternation of Generations, <a href="#Page_31">31</a>, <a href="#Page_93">93</a>, <a href="#Page_99">99</a>.</li> + +<li class='indx'>Angler-fish, <a href="#Page_39">39</a>.</li> + +<li class='indx'>Azoic, without animal life, <a href="#Page_9">9</a>.</li> + + +<li class='ifirst'>B.</li> + +<li class='indx'>Barbel, a tentacle on the lower jaw of Fish such as the Cod, <a href="#Page_52">52</a>, <a href="#Page_139">139</a>.</li> + +<li class='indx'>Barnacles, <a href="#Page_40">40</a>;</li> +<li class='isub1'>on Whale, <a href="#Page_159">159</a>.</li> + +<li class='indx'>Benthos, the animals living on the bottom of the sea, <a href="#Page_110">110</a>.</li> + +<li class='indx'>Blue-shark, <a href="#Page_121">121</a>.</li> + +<li class='indx'>Blue-whale, <a href="#Page_126">126</a>.</li> + +<li class='indx'>Bonito, <a href="#Page_121">121</a>.</li> + +<li class='indx'>Boring Mollusc, <a href="#Page_43">43</a>.</li> + +<li class='indx'>Bopyrus, <a href="#Page_170">170</a>.</li> + +<li class='indx'>Brachiolaria, <a href="#Page_112">112</a>.</li> + + +<li class='ifirst'>C.</li> + +<li class='indx'>Caller-crab, <a href="#Page_76">76</a>.</li> + +<li class='indx'>Cetacea, <a href="#Page_125">125</a>.</li> + +<li class='indx'>Cilia, minute vibratile hair-like processes on the body of some small animals, <a href="#Page_111">111</a>.</li> + +<li class='indx'>Cirripedia, a group of Crustacea to which the Barnacles belong, <a href="#Page_168">168</a>.</li> + +<li class='indx'>Cod-fish Family, <a href="#Page_52">52</a>.</li> + +<li class='indx'>Coffer-fish, <a href="#Page_63">63</a>.</li> + +<li class='indx'>Colour in shallow water animals, <a href="#Page_31">31</a>;</li> +<li class='isub1'>in deep-sea animals, <a href="#Page_137">137</a>.</li> + +<li class='indx'>Copepods, <a href="#Page_86">86</a>;</li> +<li class='isub1'>parasitic, <a href="#Page_169">169</a>.</li> + +<li class='indx'>Corals, <a href="#Page_57">57</a>.</li> + +<li class='indx'>Coral and Worm, <a href="#Page_151">151</a>.</li> + +<li class='indx'>Coral-reefs, <a href="#Page_56">56</a>;</li> +<li class='isub1'>shells of, <a href="#Page_65">65</a>;</li> + +<li class='isub1'>Anemones of, <a href="#Page_66">66</a>;</li> + +<li class='isub1'>alcyonarians of, <a href="#Page_67">67</a>;</li> + +<li class='isub1'>different forms of, <a href="#Page_68">68</a>;</li> + +<li class='isub1'>Fauna, of outer edge of, <a href="#Page_78">78</a>.</li> + +<li class='indx'>Crab-galls, <a href="#Page_158">158</a>.</li> + +<li class='indx'>Crab and Sea-weed, <a href="#Page_162">162</a>.</li> + +<li class='indx'>Crustaceans of the rocks, <a href="#Page_48">48</a>.</li> + +<li class='indx'>Ctenophores, a group of Cœlenterates, <a href="#Page_85">85</a>.</li> + +<li class='indx'>Currents, <a href="#Page_16">16</a>.</li> + +<li class='indx'>Cuttle-fish, <a href="#Page_49">49</a>.</li> + + +<li class='ifirst'>D.</li> + +<li class='indx'>Density of Sea-water, <a href="#Page_13">13</a>.</li> + +<li class='indx'>Depths of the Sea, <a href="#Page_10">10</a>.</li> + +<li class='indx'>Diatoms, minute unicellular, plants, <a href="#Page_23">23</a>.</li> + + +<li class='ifirst'>E.</li> + +<li class='indx'>Electric Organ, <a href="#Page_37">37</a>.</li> + +<li class='indx'>Eyes, <a href="#Page_27">27</a>;</li> +<li class='isub1'>of Scallops, <a href="#Page_29">29</a>;</li> + +<li class='isub1'>of larval Tunicate, <a href="#Page_30">30</a>;</li> + +<li class='isub1'>of Medusæ, <a href="#Page_30">30</a>;</li> + +<li class='isub1'>of deep-sea animals, <a href="#Page_138">138</a>.</li> + + +<li class='indx'><span class="pagenum" id="Page_181">[Pg 181]</span> +F.</li> + +<li class='indx'>Fauna, the animals living in a particular region considered as a whole.</li> + +<li class='indx'>Filograna, <a href="#Page_57">57</a>.</li> + +<li class='indx'>Fish of the rocks, <a href="#Page_51">51</a>;</li> +<li class='isub1'>of the Coral-reefs, <a href="#Page_63">63</a>;</li> + +<li class='isub1'>of the surface waters, <a href="#Page_119">119</a>;</li> + +<li class='isub1'>of the deep-sea, <a href="#Page_139">139</a>.</li> + +<li class='indx'>Fish-lice, <a href="#Page_167">167</a>.</li> + +<li class='indx'>Flying-Fish, <a href="#Page_120">120</a>.</li> + +<li class='indx'>Fur-seal, <a href="#Page_133">133</a>.</li> + + +<li class='ifirst'>G.</li> + +<li class='indx'>Gas reservoirs in Plankton, <a href="#Page_90">90</a>.</li> + +<li class='indx'>Gastropods of shallow water, <a href="#Page_45">45</a>;</li> +<li class='isub1'>of Plankton, <a href="#Page_100">100</a>.</li> + +<li class='indx'>Gelasimus, <a href="#Page_76">76</a>.</li> + +<li class='indx'>Globe-fish, <a href="#Page_63">63</a>.</li> + +<li class='indx'>Globigerina, <a href="#Page_21">21</a>, <a href="#Page_104">104</a>.</li> + + +<li class='ifirst'>H.</li> + +<li class='indx'>Hag-fish, <a href="#Page_166">166</a>.</li> + +<li class='indx'>Halobates, <a href="#Page_102">102</a>.</li> + +<li class='indx'>Hermit-crab, <a href="#Page_147">147</a>.</li> + +<li class='indx'>Herrings, <a href="#Page_123">123</a>.</li> + +<li class='indx'>Hormiphora, <a href="#Page_85">85</a>.</li> + + +<li class='ifirst'>I.</li> + +<li class='indx'>Inachus, <a href="#Page_162">162</a>.</li> + +<li class='indx'>Ipnops, <a href="#Page_138">138</a>.</li> + +<li class='indx'>Isopoda, a group of Crustaceans to which the Wood-louse belongs, <a href="#Page_139">139</a>.</li> + + +<li class='ifirst'>J.</li> + +<li class='indx'>Janthina, <a href="#Page_101">101</a>.</li> + +<li class='indx'>Jelly-fish, <a href="#Page_84">84</a>, <a href="#Page_92">92</a>.</li> + +<li class='indx'>John Dory, <a href="#Page_54">54</a>.</li> + + +<li class='ifirst'>L.</li> + +<li class='indx'>Lamprey, <a href="#Page_166">166</a>.</li> + +<li class='indx'>Larva, a young immature free individual differing in form from the Parent.</li> + +<li class='indx'>Larvæ in surface waters, <a href="#Page_109">109</a>.</li> + +<li class='indx'>Leeches, <a href="#Page_166">166</a>.</li> + +<li class='indx'>Lithothamnion, <a href="#Page_20">20</a>, <a href="#Page_57">57</a>.</li> + +<li class='indx'>Lug-worm, <a href="#Page_34">34</a>.</li> + +<li class='indx'>Lump-sucker, <a href="#Page_52">52</a>.</li> + + +<li class='ifirst'>M.</li> + +<li class='indx'>Mackerel, <a href="#Page_124">124</a>.</li> + +<li class='indx'>Madrepore, <a href="#Page_57">57</a>.</li> + +<li class='indx'>Mangrove-swamp, <a href="#Page_73">73</a>.</li> + +<li class='indx'>Medusæ, <a href="#Page_31">31</a>, <a href="#Page_92">92</a>.</li> + +<li class='indx'>Melia tesselata, <a href="#Page_148">148</a>.</li> + +<li class='indx'>Millepore and Barnacle, <a href="#Page_155">155</a>.</li> + +<li class='indx'>Mud-line, <a href="#Page_19">19</a>.</li> + + +<li class='ifirst'>N.</li> + +<li class='indx'>Nauplius larva, <a href="#Page_40">40</a>, <a href="#Page_115">115</a>.</li> + +<li class='indx'>Nekton, <a href="#Page_119">119</a>.</li> + +<li class='indx'>Noctiluca, <a href="#Page_109">109</a>.</li> + + +<li class='ifirst'>O.</li> + +<li class='indx'>Ooze, <a href="#Page_21">21</a>.</li> + + +<li class='ifirst'>P.</li> + +<li class='indx'>Palolo Worm, <a href="#Page_79">79</a>.</li> + +<li class='indx'>Parasitism, <a href="#Page_164">164</a>.</li> + +<li class='indx'>Periophthalmus, <a href="#Page_74">74</a>.</li> + +<li class='indx'>Periwinkles, <a href="#Page_45">45</a>.</li> + +<li class='indx'>Pholas, <a href="#Page_43">43</a>.</li> + +<li class='indx'>Phosphorescence, <a href="#Page_82">82</a>, <a href="#Page_107">107</a>;</li> +<li class='isub1'>of deep-sea fauna, <a href="#Page_140">140</a>.</li> + +<li class='indx'>Phyllopteryx, <a href="#Page_26">26</a>.</li> + +<li class='indx'>Physalia, <a href="#Page_97">97</a>.</li> + +<li class='indx'>Pipe-fish, <a href="#Page_25">25</a>.</li> + + +<li class='indx'><span class="pagenum" id="Page_182">[Pg 182]</span> +Plankton floating or drifting animals of a region considered as a whole, <a href="#Page_83">83</a>.</li> + +<li class='indx'>Pluteus, <a href="#Page_113">113</a>.</li> + +<li class='indx'>Porpoise, <a href="#Page_127">127</a>.</li> + +<li class='indx'>Prawn, parasite of, <a href="#Page_170">170</a>.</li> + +<li class='indx'>Pteropod, <a href="#Page_21">21</a>, <a href="#Page_102">102</a>.</li> + +<li class='indx'>Pyrosoma, <a href="#Page_108">108</a>.</li> + + +<li class='ifirst'>R.</li> + +<li class='indx'>Radiolarians, <a href="#Page_22">22</a>, <a href="#Page_160">160</a>.</li> + +<li class='indx'>Razor-shell, <a href="#Page_35">35</a>.</li> + +<li class='indx'>Red clay, <a href="#Page_21">21</a>.</li> + +<li class='indx'>Right-whale, <a href="#Page_126">126</a>.</li> + +<li class='indx'>Rocks, Fauna of, <a href="#Page_39">39</a>.</li> + + +<li class='ifirst'>S.</li> + +<li class='indx'>Sabella, <a href="#Page_153">153</a>.</li> + +<li class='indx'>Sacculina, <a href="#Page_168">168</a>.</li> + +<li class='indx'>Salps, <a href="#Page_98">98</a>.</li> + +<li class='indx'>Sandy shores, Fauna of, <a href="#Page_34">34</a>.</li> + +<li class='indx'>Sargasso, <a href="#Page_106">106</a>.</li> + +<li class='indx'>Scallop, eyes of, <a href="#Page_29">29</a>.</li> + +<li class='indx'>Scopelus, <a href="#Page_123">123</a>.</li> + +<li class='indx'>Sea-anemones, <a href="#Page_66">66</a>, <a href="#Page_163">163</a>.</li> + +<li class='indx'>Sea-bottom, <a href="#Page_18">18</a>.</li> + +<li class='indx'>Sea-elephant, <a href="#Page_132">132</a>.</li> + +<li class='indx'>Sea-horse, <a href="#Page_26">26</a>.</li> + +<li class='indx'>Sea-lilies, <a href="#Page_144">144</a>.</li> + +<li class='indx'>Sea-lion, <a href="#Page_132">132</a>.</li> + +<li class='indx'>Sea-sawdust, <a href="#Page_106">106</a>.</li> + +<li class='indx'>Sea-urchin, <a href="#Page_43">43</a>.</li> + +<li class='indx'>Sea-weeds, <a href="#Page_24">24</a>, <a href="#Page_106">106</a>.</li> + +<li class='indx'>Seal, <a href="#Page_130">130</a>.</li> + +<li class='indx'>Serpula, <a href="#Page_41">41</a>.</li> + +<li class='indx'>Shells of Coral-reef, <a href="#Page_65">65</a>.</li> + +<li class='indx'>Ship-worm, <a href="#Page_43">43</a>.</li> + +<li class='indx'>Shrimps, <a href="#Page_31">31</a>.</li> + +<li class='indx'>Siphonophores, <a href="#Page_95">95</a>.</li> + +<li class='indx'>Skates, <a href="#Page_36">36</a>.</li> + +<li class='indx'>Slime glands of Fish, <a href="#Page_165">165</a>.</li> + +<li class='indx'>Sole, <a href="#Page_37">37</a>.</li> + +<li class='indx'>Solen, <a href="#Page_35">35</a>.</li> + +<li class='indx'>Sperm-whale, <a href="#Page_127">127</a>.</li> + +<li class='indx'>Spines in Plankton, <a href="#Page_90">90</a>.</li> + +<li class='indx'>Sponge, Hermit-crab and Worm, <a href="#Page_150">150</a>.</li> + +<li class='indx'>Star-fish, <a href="#Page_44">44</a>;</li> +<li class='isub1'>method of feeding of, <a href="#Page_29">29</a>.</li> + +<li class='indx'>Stenopus, <a href="#Page_33">33</a>.</li> + +<li class='indx'>Sting-ray, <a href="#Page_36">36</a>.</li> + +<li class='indx'>Stinging of Cœlenterates, <a href="#Page_97">97</a>.</li> + +<li class='indx'>Sun-fish, <a href="#Page_122">122</a>.</li> + +<li class='indx'>Swamp-fauna, <a href="#Page_74">74</a>.</li> + +<li class='indx'>Symbiosis, <a href="#Page_146">146</a>.</li> + + +<li class='ifirst'>T.</li> + +<li class='indx'>Temperature of sea-water, <a href="#Page_11">11</a>.</li> + +<li class='indx'>Teredo, <a href="#Page_43">43</a>.</li> + +<li class='indx'>Thread-cells, <a href="#Page_97">97</a>.</li> + +<li class='indx'>Tides, <a href="#Page_15">15</a>.</li> + +<li class='indx'>Torpedo, <a href="#Page_37">37</a>.</li> + +<li class='indx'>Trepang, <a href="#Page_153">153</a>.</li> + +<li class='indx'>Trichodesmium, <a href="#Page_106">106</a>.</li> + +<li class='indx'>Tridacna, <a href="#Page_65">65</a>.</li> + +<li class='indx'>Trigger-fish, <a href="#Page_63">63</a>.</li> + +<li class='indx'>Tunicates, eye of, <a href="#Page_30">30</a>.</li> + + +<li class='ifirst'>V.</li> + +<li class='indx'>Velella, <a href="#Page_96">96</a>.</li> + + +<li class='ifirst'>W.</li> + +<li class='indx'>Walrus, <a href="#Page_134">134</a>.</li> + +<li class='indx'>Worm-tubes, <a href="#Page_163">163</a>.</li> + + +<li class='ifirst'>X.</li> + +<li class='indx'>Xenophora, <a href="#Page_162">162</a>.</li> + + +<li class='ifirst'>Y.</li> + +<li class='indx'>Yellow cells, <a href="#Page_160">160</a>.</li> + + +<li class='ifirst'>Z.</li> + +<li class='indx'>Zoophytes, <a href="#Page_30">30</a>, <a href="#Page_161">161</a>.</li> +</ul> + + + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<p class="mtb4"> +<span class="pagenum" id="Page_183">[Pg 183]</span><br> +PRINTED BY<br> +TURNBULL AND SPEARS,<br> +EDINBURGH +</p> +</div> + +<hr class="chap x-ebookmaker-drop"> + +<div class="chapter"> +<p class="p0 center"> +<span class="pagenum" id="Page_184">[Pg 184]</span><br> +“<i>A very useful series of small manuals on subjects of +<br>common interest.</i>”—<span class="smcap">Spectator.</span> +</p> +</div> + +<p class="p0 medium center">THE</p> + +<p class="p0 xxlarge center">Library of Useful Stories.</p> + +<p class="p0 medium center"><i>Small 8vo, cloth, price 1s. each Volume, +post free 1s. 2d.</i></p> + +<p class="p0 medium center">“<i>The more Science advances, the more it becomes +<br>concentrated in little books.</i>”—<span class="smcap">Leibnitz.</span></p> + +<p class="p0 medium center">I.</p> + +<p class="p0 large">THE STORY OF THE STARS.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">G. F. Chambers</span>, F.R.A.S., Author of “Handbook +of Descriptive and Practical Astronomy,” &c. +With 24 Illustrations.</p> +</div> + +<p>“Mr Chambers writes in a vigorous and attractive style, +and shows himself able to combine to an uncommon degree +scientific accuracy of statement with a clear and attractive +exposition. Beginners in astronomy who wish to acquaint +themselves merely with the outlines of a noble science will +find this volume of real service.”—<i>Speaker.</i></p> + +<p>“Told in a pleasing and attractive manner.”—<i>Athenæum.</i></p> + + +<p class="p0 medium center">II.</p> + +<p class="p0 large">THE STORY OF PRIMITIVE MAN.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">Edward Clodd</span>, Author of “The Story of Creation,” +&c. With 88 Illustrations.</p> +</div> + +<p>“It possesses the chief qualities that go to make a good +book for the average man.”—<i>Nature.</i></p> + +<p>“Well printed, well bound, profusely illustrated, and in +every respect capital material, on one of the most progressive +of sciences.”—<i>Daily Chronicle.</i></p> + + +<p class="p0 medium center">III.</p> + +<p class="p0 large">THE STORY OF THE PLANTS.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">Grant Allen</span>. With 49 Illustrations.</p> +</div> + +<p>“A brightly written, clear and accurate summary of the +functions and habits of plants.”—<i>Daily Chronicle.</i></p> + +<p>“The whole book is excellent, but special praise is due to +his exposition of the relations existing between plants and +insects. Many chapters of the story he tells must prove to the +uninitiated as exciting as a romance.”—<i>Aberdeen Free Press.</i> +<span class="pagenum" id="Page_185">[Pg 185]</span></p> + + +<p class="p0 medium center">IV.</p> + +<p class="p0 large">THE STORY OF THE EARTH IN PAST +AGES.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">H. G. Seeley</span>, F.R.S., Professor of Geology, +Geography, and Mineralogy in King’s College, +London. With 40 Illustrations.</p> +</div> + +<p>“A simple and popular summing up of the results that have +been reached by geological science.”—<i>Scotsman.</i></p> + +<p>“Told plainly and pleasantly for a popular audience.”—<i>Bookman.</i></p> + + +<p class="p0 medium center">V.</p> + +<p class="p0 large">THE STORY OF THE SOLAR SYSTEM.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">G. F. Chambers</span>, F.R.A.S. With 28 Illustrations.</p> +</div> + +<p>“His descriptions possess the double quality of simplicity +and attractiveness.”—<i>Nature.</i></p> + +<p>“He repudiates the idea that unless a man can command a +big telescope he is not in a position to do useful work in +astronomy.... The little volume is an admirable example of +science made easy without the sacrifice of strict accuracy of +statement.”—<i>Speaker.</i></p> + + +<p class="p0 medium center">VI.</p> + +<p class="p0 large">THE STORY OF A PIECE OF COAL.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">E. A. Martin</span>. With 38 Illustrations.</p> +</div> + +<p>“Treated with wonderful skill, simplicity, and thoroughness.”—<i>Bookseller.</i></p> + +<p>“Explains in simple and delightful fashion what coal is, +whence it comes, and whither it goes, and in the concluding +chapters shows how intimately it is connected with the interests +of the botanist, the geologist, the physicist, the +chemist, and the merchant.”—<i>Bradford Observer.</i> +<span class="pagenum" id="Page_186">[Pg 186]</span></p> + + +<p class="p0 medium center">VII.</p> + +<p class="p0 large">THE STORY OF ELECTRICITY.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">J. Munro</span>, Joint Author of “The Pocket-book +of Electrical Rules and Tables.” With 100 Illustrations.</p> +</div> + +<p>“Just the kind of book to give the general reader more +correct views of the subject than many a pretentious tome.”—<i>The +Electrical Engineer.</i></p> + +<p>“For general interest we must pronounce the little book +without a peer, style and matter being alike excellent.”—<i>Glasgow +Daily Mail.</i></p> + +<p>“A handy little book which has certainly the great merit +of being up to date. We anticipate a large demand for the +book.”—<i>Electricity.</i></p> + + +<p class="p0 medium center">VIII.</p> + +<p class="p0 large">THE STORY OF EXTINCT CIVILIZATIONS +OF THE EAST.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">R. E. Anderson</span>, M.A., contributor to Chambers’s +Encyclopædia, Encyclopædia Britannica, and +Dictionary of National Biography, &c. With Maps.</p> +</div> + +<p>“The author has performed a much needed service in a +masterly manner.... We have nothing but praise for the +work.”—<i>Literary World.</i></p> + +<p>“An admirable compendium of a department of knowledge +which has been greatly advanced by the research of recent +years.”—<i>Aberdeen Free Press.</i></p> + + +<p class="p0 medium center">IX.</p> + +<p class="p0 large">THE STORY OF THE CHEMICAL ELEMENTS.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">M. M. Pattison Muir</span>, M. A., Fellow and +Prælector in Chemistry of Gonville and Caius +College, Cambridge.</p> +</div> + +<p>“One of the most perfect popular introductions to science +extant.”—<i>British Medical Journal.</i></p> + +<p>“Prof. Muir tells an enthralling story of the wonderful +transformations of matter under the chemist’s magic wand. +Ignoring formulæ he appeals in homely phrase to the imagination +of the reader.”—<i>Knowledge.</i> +<span class="pagenum" id="Page_187">[Pg 187]</span></p> + + +<p class="p0 medium center">X.</p> + +<p class="p0 large">THE STORY OF FOREST AND STREAM.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">James Rodway</span>, F.L.S., Author of “In the +Guiana Forest,” &c. With about 27 Illustrations.</p> +</div> + +<p>“Contains a short description of a tropical forest, together +with some elementary lessons which can be learned by studying +the incessant struggle for existence of its varied flora.”—<i>Academy.</i></p> + +<p>“A noteworthy addition to the series in which it appears.”—<i>Scotsman.</i></p> + + +<p class="p0 medium center">XI.</p> + +<p class="p0 large">THE STORY OF THE WEATHER.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">G. F. Chambers</span>, F.R.A.S., of the Inner Temple, +Author of “Story of the Stars,” &c. With 50 +Illustrations.</p> +</div> + +<p>“An interesting volume about weather, and especially +English weather, and presents facts, ideas, and suggestions +which ordinary people will be glad to know.”—<i>St James’s +Budget.</i></p> + +<p>“Shows how the weather forecasts are drawn up at the +Meteorological Office, explains the construction and use of the +various meteorological instruments, describes the nature and +causes of such phenomena as the aurora borealis, and gives a +collection of weather facts and signs.”—<i>Literary World.</i></p> + + +<p class="p0 medium center">XII.</p> + +<p class="p0 large">THE STORY OF THE EARTH’S ATMOSPHERE.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">Douglas Archibald</span>, M.A., Fellow and sometime +Vice-President of the Royal Meteorological +Society, London. With 44 Illustrations.</p> +</div> + +<p>“One of the best of the Story series that we have read ... +the author is frequently able from his wide travels to illustrate +his remarks from his own personal experience in climates +where meteorological manifestations can be witnessed on a +grander scale than in our own country.”—<i>Nature.</i> +<span class="pagenum" id="Page_188">[Pg 188]</span></p> + + +<p class="p0 medium center">XIII.</p> + +<p class="p0 large">THE STORY OF GERM LIFE: <span class="smcap">Bacteria</span>.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">H. W. Conn</span>. With 34 Illustrations.</p> +</div> + +<p class="p0 medium center"><i>NEW VOLUMES IN PREPARATION.</i></p> + +<p class="p0 large">THE STORY OF THE POTTER.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">C. F. Binns</span>, late of Worcester Royal Porcelain +Works.</p> +</div> + +<p class="p0 large">THE STORY OF BRITISH COINAGE.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">G. B. Rawlings</span>. With Illustrations from Coins +in the British Museum.</p> +</div> + +<p class="p0 large">THE STORY OF PHOTOGRAPHY.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">A. T. Story</span>. With Illustrations.</p> +</div> + +<p class="p0 large">THE STORY OF RELIGIONS.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">E. D. Price</span>, F.G.S. With Map, &c.</p> +</div> + +<p class="p0 large">THE STORY OF THE EARTH’S SURFACE.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">H. G. Seeley</span>, F.R.S., Professor of Geology, +Geography, and Mineralogy in King’s College, +London, Author of “The Story of the Earth,” &c. +With Illustrations.</p> +</div> + +<p class="p0 large">THE STORY OF ARCHITECTURE.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">P. L. Waterhouse</span>, M.A., Associate of the +Royal Institute of British Architects. With Illustrations.</p> +</div> + +<p class="p0 large">THE STORY OF PAINTING.</p> + +<div class="blockquot"> +<p class="p0">By <span class="smcap">A. G. Temple</span>, F.S.A. With Illustrations.</p> +</div> + +<p class='center'><i>To be followed by other Volumes, of which due notice +will be given.</i></p> + +<hr> + +<p class="p0 medium center">LONDON: GEORGE NEWNES LIMITED, PUBLISHERS.</p> + +<div style='text-align:center'>*** END OF THE PROJECT GUTENBERG EBOOK 78328 ***</div> +</body> +</html> diff --git a/78328-h/images/cover.jpg b/78328-h/images/cover.jpg Binary files differnew file mode 100644 index 0000000..e9383a4 --- /dev/null +++ b/78328-h/images/cover.jpg diff --git a/78328-h/images/fig1.jpg b/78328-h/images/fig1.jpg Binary files differnew file mode 100644 index 0000000..cc15df7 --- /dev/null +++ b/78328-h/images/fig1.jpg diff --git a/78328-h/images/fig10.jpg b/78328-h/images/fig10.jpg Binary files differnew file mode 100644 index 0000000..01ded13 --- /dev/null +++ b/78328-h/images/fig10.jpg diff --git a/78328-h/images/fig11.jpg b/78328-h/images/fig11.jpg Binary files differnew file mode 100644 index 0000000..9b78f8c --- /dev/null +++ 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