Washington (AFP)

Sea otters have tough skin, can go eight minutes without breathing to fetch crabs and shellfish, and produce heat from their muscles to withstand the icy waters of the North Pacific, according to a study released Thursday.

According to this study published in the journal Science, the smallest marine mammal in North America has a unique system of energy conversion when other mammals warm up by activating their muscles through exertion or involuntary tremors.

Lead author Traver Wright of Texas A&M University told AFP that otters' water-resistant fur can limit heat loss, but not enough to survive in water-resistant waters. the Alaskan sea ice, their main habitat.

Scientists already knew that otters, which belong to the mustelid 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 mass per day.

But it was not yet known which tissues used this energy and how it was transformed into heat.

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Mr Wright and his colleagues have taken muscle samples from sea otters that have died or been collected by the Monterey Bay Aquarium, which treat them before releasing them.

They then measured their oxygen consumption.

- Make heat without doing anything -

In general, animals produce heat by activating their muscles, but in otters, the majority of the metabolic energy produced by sugars and fat is used to supply the body with heat from their muscles, without necessarily getting them. contract.

"They are very good at generating heat without doing anything," explained Dr Wright.

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This energy would be wasted for land mammals, like humans, "but if you are an animal that wants to warm up, this + wasted + energy is fine" for maintaining a temperature of 37 degrees Celsius in ice water, a t -he adds.

This ability is present in otters from birth, regardless of whether they are wild or in captivity.

Like other marine mammals, they could have developed it when their ancestors took to the sea 50 million years ago, but this hypothesis needs to be confirmed by further research.

Knowledge of otter metabolism could also help cure obesity in humans, according to Traver Wright.

"If we can manage to increase the production (of heat) and the basal metabolism, we can theoretically stimulate the human metabolism and make it burn more calories", even without playing sports, he explained.

© 2021 AFP