G2 LIFE IN THE SEA [PART I 



such as the brittle stars, and the stalked feather stars which are 

 the "last survivors of a large and important order which flourished 

 in past geological ages," occur, and the sea cucumbers or Holo- 

 thurians are also found. Sponges form an important part of the 

 deep-sea fauna. Corals, zoophytes and their allies, though not so 

 numerous as the sponges, are nevertheless well represented. 

 Molluscs and Crustacea in all their classes are found. Worms are 

 found in the red clay of the deepest abysses. Fishes are uniformly 

 and relatively abundantly distributed. Generally speaking all the 

 shallow water groups have their deep water allies, but in the 

 depths there are strange adaptations and bizarre forms. The 

 variety of animal groups present, the numbers of species, and the 

 curious contrivances for obtaining food all point, it has been said, 

 to the conclusion that in the deep sea the struggle for existence 

 is no less severe than in the shallow waters near the land. Possibly 

 then the abundance of life in the depths is great and there is 

 an insufficiency of food. This condition would produce a struggle 

 for existence. 



Plants are, as we shall see, the " producers of the sea." They 

 alone (with some of those " borderland " creatures which we have 

 difficulty in classing) can form organic substance out of inorganic 

 material. If then plants are absent at those comparatively 

 shallow depths at which light fails to penetrate the sea how can 

 the fairly abundant deep-sea population obtain its food ? Obviously 

 these animals cannot live wholly on each other like the inhabitants 

 of the Scottish village who earned a living by taking in each 

 others' washing ! Food must be conveyed to " denizens of the 

 deep " from some outside source, and as a matter of fact we find 

 that the majority of the abyssal animals feed on the bottom 

 deposits. We have seen that with the exception of perhaps the 

 red clay much the greater part of the deep-sea deposits is formed 

 from organic remains. All the organisms which make up the 

 organic oozes live in the upper productive la^-ers of the sea and 

 when they die their bodies fall to the bottom. At the low 

 temperature found there bacterial activity is largely inhibited and 

 therefore putrefactive processes are carried on very slowly, so that 

 for a considerable time after they reach the sea floor planktonic 

 organisms, like diatoms or protozoa, must retain a considerable 



