Oxygen Consumption and Activity in Closely Related Amphipod Populations from Cave and Surface Habitats

In contrast to other cave animals, metabolic rate of amphipods was not reduced in cave populations as compared to surface populations. In the genus Stygonectes the cave-limited S. emarginatus and S. spinatus had no lower standard metabolic rate than a surface seep population of S. tenuis potamacus. Cave ecotypes of Gammarus minus showed no lower standard or routine metabolic rate and no higher activity level or locomotor efficiency than surface spring ecotypes. One possible reason for these results is that the caves in which these amphipods were found are probably not food limited.