THE DEEP SEA ANIMALS 1 93 



there are not nearly so many of them in the deep seas as are 

 to be found along the shores and in fresh water. 



Of all the animals of the ocean floors the mud-swallowing 

 echinoderms are perhaps the most abundant and diversified 

 and the most generally distributed; but all the groups repre- 

 sented also occur in shallow water except for a small number of 

 minor types. The most conspicuous of these echinoderms, be- 

 cause most strange to us, are bizarre sea-cucumbers and star- 

 fish, and soft and flexible shelled urchins. Stalked crinoids 

 rooted in the ooze or firmly attached to stones or other ob- 

 jects are characteristic of the deeps, but all the groups repre- 

 sented, like all of those to which the more abundant unstalked 

 forms belong, come up into shallow water, with possibly one ex- 

 ception. The crinoids most important from the standpoint of 

 the life of past ages, the Pentacrinus of our text books and the 

 curious Holopus, so far from being deep sea animals live, at 

 Barbados, in 30 feet or less so that they can be seen from the 

 surface with a water-glass. 



Sponges with silicious skeletons are often very abundant in 

 the deeps, especially near land. One of the chief trials of a 

 deep sea naturalist is sorting over a catch with these things 

 in the mud. Their spicules are sharp as needles, glassy and 

 transparent, and scattered ever}'where, so that the sight of 

 sponges always means sore hands. Sailors, no matter how 

 callous they may be toward other forms of life, quickly learn 

 to recognize silicious sponges. 



The coelenterates are the only group of animals of which a 

 large proportion of the t}^es are confined to deep water. They 

 are abundant here, and of many different sorts. Especially 

 characteristic are the sea-pens and umbellularians and the curi- 

 ous anemones. There are many corals, largely solitary ones, 

 but no massive t}'pes, and numerous alcyonarians and allied 

 creatures. 



Various sea-squirts occur, both simple and compound. 



Crustaceans are abundant, of all the principal marine groups 

 except the king crabs and the squillas, though barnacles are 



