sAccording to this study published in the journal Science, North America’s smallest marine mammal possesses a unique system for converting energy when other mammals warm up by activating their muscles through exertion or involuntary tremors. The waterproof fur of otters can limit heat loss, but not enough to survive in the water-resistant waters of Alaska sea ice, their main habitat, lead author Traver Wright of Texas A&M University told AFP.
Scientists already knew that otters, which belong to the mustelid family, burn a lot of energy, about three times that of mammals of the same size, and can consume up to 25% of their body mass per day. But it is not yet known which tissues use this energy and how it is converted into heat.
Mr. Wright and colleagues took muscle samples from sea otters that had died or were collected by the Monterey Bay Aquarium, which processes them before releasing them. Then they measured their oxygen consumption.
Take a break without doing anything
Generally, animals produce heat by activating their muscles, but in otters, the majority of the metabolic energy produced by sugars and fats is used to supply the body with heat from their muscles, without the need for contraction.
“They’re very good at producing heat without doing anything,” Dr. Wright explained. This energy would be wasted on terrestrial mammals, like humans, “but if you’re an animal that wants to heat up, this ‘wasted’ energy is good” for maintaining a temperature of 37 degrees Celsius in ice water, A- he added.
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 went to sea 50 million years ago, but this hypothesis needs to be confirmed by further research.
According to Traver Wright, knowledge of the metabolism of otters can help treat obesity in humans. “If we can increase (heat) production and basal metabolism, we can theoretically stimulate the human metabolism and make them burn more calories,” he explained, “even without exercise.”
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