How Otters’ Muscles Enable Their Cold, Aquatic Life

Otter Floating on Water

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Otter drifting on water’s surface area. Credit: Tray Wright/Texas A&M University (Image acquired under USFWS Marine Mammal Permit No. MA-043219 to R. Davis)

Texas A&M scientists discovered that the little mammals are internally warmed by thermogenic dripping from their skeletal muscle, which raises their metabolic rate.

Sea otters are the tiniest marine mammal. As cold-water occupants, remaining warm is a leading concern, however their thick fur just presumes. We have actually long understood that high metabolic process creates the heat they require to endure, however we didn’t understand how they were producing the heat — previously.

Researchers just recently found that sea otters’ muscles utilize enough energy through leakage respiration, energy not utilized to carry out jobs, that it represents their high metabolic rate. The finding discusses how sea otters endure in cold water.

Physiologist Tray Wright, research study assistant teacher in Texas A&M University’s College of Education & Human Development, performed the research study in addition to coworkers Melinda Sheffield-Moore, a professional on human skeletal muscle metabolic process, Randall Davis and Heidi Pearson, marine mammal ecology professionals, and Michael Murray, vet at the Monterey Bay Aquarium. Their findings were released in the journal Science.

Otter Biorender

Sea otters’ muscles utilize enough energy through leakage respiration that it represents their high metabolic rate, which keeps them warm in cool water. Credit: Tray Wright/Texas A&M University, produced with

The group gathered skeletal muscle samples from both northern and southern sea otters of differing ages and body masses. They determined breathing capability, the rate at which the muscle can utilize oxygen, discovering that the energy produced by muscle benefits more than simply motion.

“You mostly think of muscle as doing work to move the body,” Wright stated. “When muscles are active, the energy they use for movement also generates heat.”

Wright stated that due to the fact that muscle comprises a big part of body mass, typically 40-50% in mammals, it can warm the body up rapidly when it is active.

“Muscles can also generate heat without doing work to move by using a metabolic short circuit known as leak respiration,” Wright stated.

A kind of muscle-generated heat we are more acquainted with is shivering. Wright stated this uncontrolled motion enables the body to trigger muscle by contracting to produce heat, while leakage respiration can do the exact same without the tremblings.

Wright stated among the most unexpected findings was that the muscle of even newborn sea otters had a metabolic rate that was simply as high as the grownups.

“This really highlights how heat production seems to be the driving factor in determining the metabolic ability of muscle in these animals,” Wright stated.

Sea otters need a great deal of energy to reside in cold water. They consume to 25% of their body mass daily to stay up to date with their day-to-day activities and sustain their high metabolic process.

“They eat a lot of seafood, including crabs and clams that are popular with humans, which can cause conflict with fisheries in some areas,” Wright stated.

Wright stated we understand how vital muscle is to animals for activities like searching, preventing predators and discovering mates, however this research study highlights how other functions of muscle are likewise vital to animal survival and ecology.

“Regulating tissue metabolism is also an active area of research in the battle to prevent obesity,” Wright stated. “These animals may give us clues into how metabolism can be manipulated in healthy humans and those with diseases where muscle metabolism is affected.”

As for future research study, Wright stated there is still a lot we don’t learn about otters, consisting of how they manage their muscle metabolic process to show up the heat as needed.

“This is really just the first look into the muscle of these animals, and we don’t know if all the various muscle types are the same, or if other organs might also have an elevated ability to generate heat,” Wright stated.

Reference: “Skeletal muscle thermogenesis enables aquatic life in the smallest marine mammal” by Traver Wright, Randall W. Davis, Heidi C. Pearson, Michael Murray and Melinda Sheffield-Moore, 9 July 2021, Science.
DOI: 10.1126/science.abf4557