Metabolism of Small Mammals, With Remarks on the Lower Limit of Mammalian Size

Abstract

Metabolic rate was detd. in a closed chamber apparatus. All animals were tested at about 24 C and were not postabsorptive. All were adults. A resting shrew consumes O2 more rapidly than does a.mouse of the same size. The curves suggest why no adult mammal weighs less than 2.5 g. A mammal smaller than this could not get enough food to support its infinitely rapid metabolism. Although some young mammals are smaller, their low body temp. depresses their metabolism.