STUDIES ON THE PHYSIOLOGICAL VARIATION BETWEEN TROPICAL AND TEMPERATE ZONE FIDDLER CRABS OF THE GENUS UCA. III. THE INFLUENCE OF TEMPERATURE ACCLIMATION ON OXYGEN CONSUMPTION OF WHOLE ORGANISMS

Abstract

The O2 consumption of fiddler crabs from various geographical areas was determined after various periods of thermal acclimation. The temperate zone species, U. pugnax, showed a significantly higher metabolic rate after acclimation to 15[degree] C than warm-acclimated forms when determined at temperatures below 27[degree]. When animals were starved during thermal acclimation, the tendency for a shift in respiratory metabolism was apparent by day 6-8 and then was lost. Feeding maintained this pattern of acclimation for at least 21 days. U. rapax from Jamaica did not show any shift in respiratory response during acclimation to 15[degree] except at 36[degree], where the O2 consumption of cold-acclimated forms was higher than warm-acciimated animals. Population samples of U. rapax from Florida responded metabolically like temperate zone animals at low temperatures and tropical animals at high temperatures. Results showed that during the evolution and distribution of fiddler crabs different metabolic patterns during thermal acclimation have resulted.