TEMPERATURE DEPENDENCE OF BREATHING RATE IN CARP

Abstract

The breathing rates of Cyprinus carpio at constant temperatures between 4[degree] and 39[degree]C, after complete acclimation at these temperatures and plotted against temperature on semi-log coordinates, show a homeostatic zone at intermediate temperatures. While homeostasis is complete, within this zone, in small fishes (20 g) it diminishes gradually with increasing size, to disappear entirely in the largest ones (2050 g). For fishes of a given size the degree and the range of homeostasis may differ. Upper lethal temperatures decrease also with increasing size. The method is thought to be useful for adequate description of physiologic variation without killing the experimental animals. Results are discussed in the light of physiologic and evolutionary concepts.