62 



THE BIOLOGY OF MARINE ANIMALS 



values within 4% of sea water, and most within 1 %. In marine fishes, 

 which regulate osmotically and keep their blood concentrations below 

 200 mM, the internal chloride level is directly determined by the homoi- 

 osmotic powers of the species. 



Physiological Media 



Suitable physiological media for marine animals are described in the 

 appendix (p. 675). Some of these are based on analyses of body fluids, 

 others have been determined empirically. 



Hydrogen Ion Concentration. Sea water is alkaline, about pH 8*1. The 

 body fluids of marine animals are generally more acid than sea water, 

 usually above neutrality, but slightly below in some species. Some values 

 for several species are shown in Table 2.1 1. A small variation in hydrogen 



TABLE 2.11 

 Hydrogen Ion Concentrations (pH) of Body Fluids 



(Various sources) 



