Handbook of Paleontology 81 



Life in Pelagic and Abyssal Realms 



The life of the pelagic and abyssal realms will be 

 discussed first and more briefly. The plant and animal 

 associations of the shallow waters and the strand area 

 are of greater importance as an introduction to a sur- 

 vey of the geologic formations, and therefore, it is 

 only proper to have a lengthier discussion of these 

 life conditions and associations, which will be given 

 later in a separate chapter. It has been pointed out 

 that there is practically nothing in the sea which cor- 

 responds to the plant feeders of the land nor is there 

 anything to correspond to the vegetation of the land 

 except the seaweeds fringing the shore in the shallow 

 waters and masses of seaweeds floating in the open 

 ocean, such as the Sargasso Sea. There are certain 

 small crustaceans (Copepods) which feed partially up- 

 on plants and occur in such numbers as to be compar- 

 able to a certain extent to plant feeders on land. There 

 are also a few plant-eating mollusks, worms and echi- 

 noderms, but they do not occur in large enough num- 

 bers to be of much importance, so that the animals of 

 the sea mainly fall into two divisions: animals living 

 upon microscopic organisms and those preying upon 

 one another. The shores of the sea are washed by 

 waters bearing untold numbers of microscopic plants, 

 small crustaceans and creatures feeding upon these. 

 The conditions at the shore are very different from 

 those in the open sea. Facilities for attachment are 

 offered by rocks, stones, mud, sand, to a certain ex- 

 tent, and seaweeds. Plants, such as eel-grass and sea- 

 weeds provide shade and hiding places and the vegeta- 

 ble detritus formed where they die serves as an im- 

 portant part of the food of shore animals. Attached 



