How sea otters stay warm
Scientists have long known that sea otters run hot. Lacking the layer of blubber that insulates whales and polar bears, they generate heat with a metabolic rate three times faster than any other creature of their size. Yet exactly how sea otters do this has always been a mystery, until now. A new study has determined that the animals’ warming secret lies in the mitochondria in their muscle cells. When mitochondria—often called the powerhouses of cells—break down sugar to extract energy, protons pop through a membrane via tiny spin
ning spores. When the protons are too numerous for the spores to handle, they seep across the membrane in other ways, producing lots of heat in the process. In a lab test, the researchers found that sea otters experienced significantly more “proton leak” than any other animal tested, including Iditarod sled dogs. And while metabolic capacity is usually linked to activity level, sea otters have the same high rate whether they’re being active or not. “That heat generation,” Traver Wright, from Texas A&M University, tells The New York Times, “is really the driving force of their metabolic development.”