Skeletal muscle thermogenesis enables aquatic life in the smallest marine mammal

Abstract

Keeping warm when small Several mammal species live in cold-water environments, enabled by adaptations such as blubber and large size. A notable exception to this rule is the sea otter, a species that is orders of magnitude smaller and skinnier than the others. It is known that the sea otter's unusually thick fur helps, but Wright et al. show that they are also internally warmed by thermogenic leak from skeletal muscle, a process that elevates their metabolic rate three times above that expected for their size. This mechanism is present even in infants with immature muscles, providing these animals with internal warmth from birth. Science , abf4557, this issue p. 223