Sea Otters Generate Heat Without Shivering

Sea Otters‘ muscles have a greater capacity to turn food directly into heat than those of any other animal of a similar size. The findings explain how these small animals stay warm in cold waters. Most marine mammals have large bodies insulated by a thick layer of blubber to help them retain heat.

Sea Otters are relatively small and usually weigh between 14 and 45 kilograms, with only the air trapped in their fur for insulation. They have the densest fur of any mammal, but this isn’t enough to keep them warm, so they have to burn lots of energy.Their metabolic rate is around three times higher than normal for a mammal of their size, which makes it the highest of any mammal that weighs more than a kilogram.

Traver Wright at Texas A&M University in College Station said that they are high and they aren’t aware where this energy was coming from. So researchers studied tiny pieces of living muscle tissue from both northern Sea Otters and southern Sea Otters. It wasn’t necessary to kill animals to obtain the specimens, some samples came from rescued animals that were undergoing surgery to treat injuries.Muscles generate heat when they move and many animals shiver when they get cold, but constant shivering isn’t a great strategy for a creature that lives and hunts in chilly waters. Instead, the mitochondria inside the otters’ muscle cells produce heat directly.

All mitochondria use the energy derived from burning food to pump out protons, creating a proton gradient. Normally, when protons flow back into mitochondria during this process, this potential energy is used to make an energy-rich molecule called adenosine triphosphate. This fuels processes that require energy, such as muscle contractions.