CHAPTER VII 

 ANIMALS OF THE SEA FLOOR 



BY W. T. CALM AN AND G. P. FARRAN 



IN dealing with the fauna of the sea bottom it is 

 necessary to make use of some convenient and natural 

 classification of the subject. It has long been recog- 

 nized that, in passing from the shallow water surround- 

 ing the shore to the abysses of the ocean, we find many 

 striking changes in the character of the inhabitants 

 associated with the increasing depth ; and a classifi- 

 cation based on the depth at which the animals live is 

 a more or less natural one. While those areas or zones 

 of depth which are commonly accepted are marked 

 out, rather on account of their physical features than 

 because they possess separate faunas sharply defined 

 from each other, still the assemblage of animals found 

 in each zone, taken as a whole, differs considerably 

 from those of the other zones, and may conveniently 

 be dealt with apart from them. 



The zones of depth usually distinguished in European 

 seas are based on those originally defined by Edward 

 Forbes in the middle of the last century. These were 

 the Littoral Zone, the Laminarian Zone, the Coralline 

 Zone, and the region of Deep-Sea Corals. For the last 

 two may be substituted the Continental Shelf and the 

 Continental Slope, and to the list may be added the 

 ocean floor, a region which in Forbes's day was believed 

 to be devoid of living inhabitants, but which more 



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