Sea Otters Does Not Freeze in Extremely Cold Water, Mammals Have Unique Capability of Producing Heat

Sea otters are known to be excellent swimmers, complete with muscular bodies and webbed feet that enable them to cut through the water easily.

They are like famous swimmer Michael Phelps too, that they are unique in their abilities, capable of succeeding where other mammals of the same size would not stand a chance.

According to an INVERSE report, sea otters live in chilly waters that can reach between 32 and 59 degrees Fahrenheit for temperatures. Usually, mammals living in this type of environment endure the cold through blubber or being huge.

Previous research showed scientists were not sure these comparatively tiny animals, averagely males, are four feet in length, managed to keep a metabolism equivalent to mammals thrice their size. Now, a new study refers to a quirk of their anatomy to answer-distinctive skeletal muscles.

Sea Otters' Skeletal Muscle

The new study's lead author, Texas A&M University assistant professor Traver Wright said, their work demonstrates how the sea otters' skeletal muscle is well appropriate to produce heat, which is crucial for these tiny marine animals to endure the cold water.

Indeed, the world's smallest mammals, as well as their tiny body size, are putting them at a disadvantage when it comes to enduring the cold waters of the North Pacific.

A lot of larger marine mammals like whales are using fatty deposits identified as blubber to preserve heat in their bodies.

Without such blubber, sea otters retain heat in their densely packed hair, although even that mechanism is not adequate to maintain a core body temperature of 98.6 Fahrenheit.

If the body temperature of the body drops below this core temperature for too long, like humans, they will die. In this research, the team wrote, Polar and tiny-bodied marine mammals are specifically susceptible to heat loss and necessitate increased heat production to keep their body temperature.

Sea otters, in turn, adjusted in another way--- their bodies produce a basal metabolic rate that is thrice the small-sized mammals' predicted rate.

Basal Metabolic Rate

Wright explained basal metabolic rate is vitally the minimum metabolism needed for an animal to retain basic bodily function minus moving, eating, and digesting.

The increased basal metabolic rate is an adjustment to conserve heat in an environment with low temperatures, also called "thermogenic hypermetabolism."

Prior to this research, researchers have not completely understood the mechanisms that underlie the thermogenic hypermetabolism of the otter and how it enables them to thrive in cold environments.

Wright, together with his colleagues, hypothesized there might be some link between the unusually high basal metabolic rate of the sea other and its ability to survive on the cold North Pacific waters.

According to Wright, past studies suggested that the basal metabolic rate of the sea otter was around thrice higher than one would predict based on their size, which specifies that their body burns a lot of energy at rest.

Considering that the researchers speculated the hypermetabolism of the sea otter was associated with thermogenesis, which, according to ScienceDirect, is a function that allows mammals to stay warm by producing heat through some tissues and skeletal muscles.

Leak Metabolism

Sea otters are warming themselves through something called "mitochondrial leak" in their skeletal muscles; the study, Skeletal muscle thermogenesis enables aquatic life in the smallest marine mammal, published in Science, found.

Also called "leak metabolism," a previous study has found this may also help hedgehogs and other mammals stay alive in cold temperatures.

Mitochondria are small organelles found in the cells that generate energy to keep one warm and help stay alive. Scientists were able to associate this leak metabolism in the skeletal muscles of the sea otter to its respiratory capacity, its oxygen consumption rate, helping explain the reason its basal metabolic rate is quite high compared to other mammals.

Wright explained, the leak metabolic capacity in muscle tissue is high enough to explain the hypermetabolism, as explained in a similar EurekAlert! the report demonstrated previously in sea otters.

In addition, the leak metabolic capacity of the sea otter is quite high that it exceeds the same capacity in even Alaskan huskies and energetic Iditarod sled dogs.

Such values are higher than the comparable measures reported for any identified mammal, the team wrote in their study.

Related information about sea otters is shown on BBC Earth's YouTube video below:

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