SEA OTTERS ARE UNIQUE

by Whit Gibbons

August 9, 2009

Sea otters are on my top ten list of "most appealing mammals," along with pandas, beluga whales, meerkats, and, of course, puppies. But sea otters are not just cute, they are also one of the most resilient animals in the world. Which is a good thing, because in addition to living in a harsh habitat, they were nearly hunted to extinction for their fur.

These engaging creatures come as close as most animals get to qualifying for the label "unique." Being unique is not easy because you have to be the only one in a category. Sea otters are not the only marine mammal, which includes dolphins, seals, and whales, but they are the smallest. They are not the only animal in the weasel family, which includes badgers, skunks, and wolverines, but they are the only one without the scent glands that produce a strong-smelling musk that is characteristic of the rest of the family.

In the one-of-a-kind category sea otters are the only marine mammal that has no blubber or other insulating layer of fat to help it survive in cold waters. Instead, they have the densest fur among all mammals (more than a million hairs per square inch!), which traps air that provides insulation. The density of hair among humans is typically less than 3,000 hairs per square inch. Sea otters can weigh up to a hundred pounds, making them one of the heaviest members of the weasel family, but they can float with ease because of air trapped in the fur.

Their diet includes fish, abalones and other mollusks, sea urchins, crabs, and other sea creatures, most of which they dive to the sea floor to obtain. They have lungs that are more than twice the size of most comparably sized mammals. They have been known to dive as deep as 300 feet and commonly stay under water two to four minutes. Among the myriad traits that set them apart from other animals is their use of tools; sea otters are one of the few mammals known to employ tools. They use rocks to dislodge abalones, which attach themselves to hard surfaces and must be pried loose. Furthermore, a sea otter, which typically swims on its back while eating, will set a rock on its belly and open the abalone shell by pounding it against the rock.

I rubbed my hand over a sea otter pelt once; it was the softest fur I have ever felt. Their fur was the reason for their near demise, initially at the hands of the Russians in the 1700s. In fact, the primary reason for the Russian occupation of Alaska before we bought it for a few cents an acre was the sea otter fur trade. At the time, sea otter pelts were considered the most valuable in the world.

The Russians recruited people native to the Aleutian Islands for the fur trade beginning in 1741, when the number of sea otters worldwide was estimated to be as high as 300,000. The unregulated killing of sea otters continued in most parts of the animal's geographic range from northern Japan, across the Aleutians, and down the western U.S. coast to Baja California until 1911. In that year four nations--Russia, Japan, Great Britain, and the United States--established a treaty to protect the species. At the time fewer than 2,000 sea otters were left in the world, and some estimates place the number as low as 1,000.

We came very close to wiping out this marvelous species through unsustainable harvesting. We actually finished the job on the East Coast with the sea mink, which became extinct in the 1800s as a result of overhunting for the fur trade. Sea otters are tough, but they take several years to mature, usually have only one pup, and can live more than 20 years. Taken together those factors mean the species cannot recover quickly from a population decline.

In the past hundred years the worldwide population has gradually increased. Although exact numbers are hard to come by, about 100,000 wild sea otters are estimated to be alive today. I am glad the sea otter is still around to be placed on my top ten list of most appealing mammals.

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