No Icy Otters

As the smallest marine mammal, sea otters have fascinated scientists with their ability to stay warm despite the cool ocean temperatures where they live. While researchers knew the animals’ high metabolism produced enough heat for survival, they only recently confirmed how that heat can be produced: a form of muscle-generated heat from leak respiration.

The research team composed of Drs. Tray Wright ’99, Melinda Sheffield-Moore ’87, Randall Davis, Heidi Pearson ’08 and Michael Murray emphasized that discoveries such as this can reveal how non-traditional muscle functions are crucial for animal survival and ecology.

“Regulating tissue metabolism is also an active area of research in the treatment of obesity,” Wright said. “These animals may give us clues into how metabolism can be manipulated in healthy humans and those with diseases where muscle metabolism is affected, although any such intervention is years away.”

The research team collected skeletal muscle samples from sea otters of varying ages and body masses. They measured respiratory capacity, the rate at which the muscle can use oxygen, and found that the energy produced by muscle is good for more than just movement.

“We know that when muscles are active, the energy they use for movement generates heat,” Wright said. “Now we’ve learned that muscles can also generate heat without doing work to move by using a metabolic short circuit called leak respiration.”