CHAPTER XI 



METABOLISM IN THE SEA 



ON taking a general view of life in the sea, it 

 becomes possible to group the multitudinous 

 assemblage of organisms contained there under 

 three great categories, according to their general 

 habits and method of occurrence. There are first 

 of all a great number of plants and animals which 

 live throughout the greater part of their existence 

 permanently rooted to the sea-bottom, either in 

 deep or in shallow water, or burrowing among 

 the deposits which cover the sea-floor. These 

 are the sea-weeds, the zoophytes, animals like crabs, 

 lobsters, and their kindred, star-fishes and sea-urchins, 

 molluscs like the mussel, oyster, or cockle, sponges, 

 sea-anemones, and a host of other creatures which 

 are either sedentary, or which, if they do move 

 about, have a very limited range of movement. 

 All these organisms have been grouped together 

 by Haeckel and called the Benthos. They are 

 found everywhere on the sea-floor, though they 

 are most abundant in fairly shallow water, down, 



