The otters warm up effortlessly

Sea otters have hard skin, can reach crabs and shellfish for eight minutes without breathing, and produce heat from their muscles to withstand the icy waters of the North Pacific, according to a study published on July 8, 2021.

Animals that burn a lot of energy

According to this study published in the journal Science, the smallest marine mammal in North America has a unique energy conversion system when other mammals warm up by activating muscles with effort or involuntary trembling. Lead author Traver Wright of the University of A&M in Texas told AFP that water-resistant otter fur can limit heat loss, but not enough to survive in water-resistant water. Scientists already knew that otters, which belong to the mustelide family, burn a lot of energy, about three times more than mammals of the same size, and that they can consume up to 25% of their body weight daily. But it was not yet known which tissues use that energy and how it is converted into heat. Mr. Wright and his colleagues took samples of sea otter muscles that had died or were collected by the Monterey Bay Aquarium, which treated them before releasing them. They then measured oxygen consumption.

Warm up … doing nothing

In general, animals produce heat by activating muscles, but in the otter most of the metabolic energy produced by sugars and fats is used to supply the body with heat from their muscles without necessarily contracting them. “They are very good at producing heat without doing anything“Dr. Wright explained. This energy would be lost to terrestrial mammals, like humans.”but if you’re an animal that wants to warm up, that ‘lost’ energy is fine“to maintain a temperature of 37 degrees Celsius in ice water, he added. This ability is present in otters from birth, whether they are wild or in captivity.

Like other marine mammals, they may have developed it when their ancestors went to sea 50 million years ago, but this hypothesis needs to be confirmed by further research. Knowledge of otter metabolism could also help treat obesity in humans, according to Traver Wright. “If we manage to increase production (heat) and basal metabolism, we can theoretically stimulate human metabolism and make it burn more calories.“, even without playing sports,” he explained.

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