192 



THE BIOLOGY OF MARINE ANIMALS 



During periods of anaerobiosis in lamellibranchs, when the valves are 

 shut, the blood and mantle fluids show only a slight increase in acidity, 

 while the C0 2 and calcium content increase greatly, along with C0 2 - 

 binding capacity {Mercenaria, My a, Ostrea). In Mercenaria mercenaria , 

 for example, the C0 2 content increases from 6-150 vols% in the mantle 

 fluid of animals kept in air for 15 days (Fig. 4.25). As the result of 



10 20 30 40 50 60 10 

 Carbon Dioxide Tension (mm Hg) 



Fig. 4.25. Curves for carbon dioxide Combining Ability of Mantle Fluid 

 in Mercenaria mercenaria after Various Periods of Exposure to Air. 



(From Dugal (37).) 



anaerobiosis, non-volatile acid is produced, and this is buffered by calcium 

 eroded from the shell, resulting in the accumulation of Ca(HC0 3 ) 2 and 

 CaL 2 , where the latter represents the buffering of some non-volatile acid 

 such as lactic acid (37, 114). 



REFERENCES 



1. Alcock, A., A Naturalist in Indian Seas (London, John Murray, 1902). 



2. Allen, D. W. and Wyman, J., Jr., "The oxygen equilibrium of hemerythrin 

 of Arenicola cristata," J. Cell. Comp. Physiol., 39, 383 (1952). 



