CHAPTER V 



^JUSTMENT TO CONDF 

 OF AQUATIC LIFE 



lor 



INDIVIDUA] 

 ADJUSTMEN 



O infinitely varied are 

 the fitnesses of aqua- 

 tic organisms for the 

 conditions they have 

 to meet that we can 

 only select out of a 

 worldful of examples a 

 few of the more wide- 

 spread and significant. 

 We shall have space 

 here for discussing 

 only such adaptations to life in the water as are common 

 to large groups of organisms, and represent general 

 modes of adjustment. First we will consider some of 

 the ways in which the species is fitted to the aquatic 

 conditions under which it lives, and then we will take 

 note of some mutual adjustments between different 

 species. 



The first of living things to appear upon the earth 

 were doubtless simple organisms that were far from 



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