160 



THE BIOLOGY OF MARINE ANIMALS 



is preserved at a relatively high level in winter. Other species become 

 dormant, e.g. beach flea Talorchestia megaJophthalma, and show no adap- 

 tive rise in winter metabolism (41, 42, 79, 142, 162, 163). 



Many instances of temperature compensation or acclimatization involve 

 a shift of the metabolism temperature curve along the abscissa. Thus in 

 metabolic adaptation to cold, the entire 2 consumption curve is displaced 

 towards low temperatures. Theoretically, a low temperature-coefficient 



48° N 

 39°N 



J4°/V 



8 10 12 14 



Temperature (°C) 



16 



18 



20 



Fig. 4.11. Pumping Rates of the Mussel My tikis califomianus, 

 at Different Temperatures 



Measurements made on three samples of animals from different localities (latitude 

 shown after each curve). Animals weighed 50 g. (From Bullock (21).) 



(do) would be advantageous in offsetting the effects of temperature 

 changes, but evidence for such is still equivocal (Table 4.4) (21, 142). 



Adaptations to temperature differences associated with geographic 

 distribution are now well established for a series of poikilotherms. Respira- 

 tory rates and heart rates of some but not all cold-water polychaetes and 

 Crustacea are often higher than those of comparable warm-water forms 

 when measured at the same intermediate temperature; mussels (Mytilus 

 califomianus) have greater pumping rates in higher than in lower latitudes, 

 other factors being equal (Fig. 4.11) (21, 34a). 



