Temperature Relations of Ectotherms: A Speculative Review

Abstract

The interpretation of the temperature relationships of ectothermic animals has already run through two phases and we now appear to be experiencing the beginning of a third. In the first phase ectotherms were regarded as being at the mercy of the environment, an interpretation best expressed by Krogh's so-called ``normal curve'' (Krogh, 1914). In the second phase, dating from about 1936 (Fox, 1936; Spärck, 1936; Thorson, 1936; Schlieper, 1950; Precht et al., 1955; Bullock, 1955; Prosser, 1958), the emphasis was placed upon the homeostatic character of metabolic processes. And now, in the third phase, the metabolism of such organisms is seen to be considerably more complicated: various temperature ranges are thought to be associated with different systemic states, involving, to some extent, specific ionic distributions as well as alternative enzyme and metabolic patterns.