Sea otters are comfortable in cold waters. (archive image)
Marine mammals use their muscles to produce heat rather than movement, according to a study published Thursday in the journal Science. Unlike seals and whales, for example, they do not have thick layers of fat in cold waters.
Sea otters have lush, water-resistant fur. However, this alone is not enough to compensate for the heat loss in cold waters, otters expert Travers Wright of Texas A&M University told AFP. How animals stay warm has always been a mystery.
Sea otters have been known to expend a great deal of energy – about three times what is typical for mammals of their size. In extreme cases, animals burn up to 25% of their body mass in one day. Wright and his team have now focused on the question of how and for what purpose this energy is used.
They took muscle samples from dead sea otters and examined live animals from the Monterey Bay aquarium. The main function of muscles in general is to move the body. However, in otters a large portion of the metabolic energy is lost as heat rather than being used for work such as muscle contraction.
“One of the interesting things we found is that they’re really good at generating heat by being inefficient,” Wright describes. For terrestrial mammals such as humans, this sounds like a waste, “but if you’re an animal trying to warm up, that wasted energy and warmth is a good thing.” (SDA)