The weasels (or more formally the Mustelidae) are a family of small-to-medium-sized carnivores which have done quite well for themselves in an evolutionary way. There are some 70 species in the family, members of which are, or were, found everywhere except in Australia, Madagascar and Antarctica. The animals have diversified marvelously and have adapted to fill a great variety of biological niches. Thus, among the North American weasels there are fishers and wolverines, big powerful hunters who forage in the deep-snow country. The marten is a treetop hunter, more agile than any squirrel. The badger has become a digger, something of a subterranean predator in the hot, dry prairies. The mink operates in marshland habitats, and the river otter developed webbed feet and other equipment that allow it to function as a semi-aquatic carnivore. Of all the North American weasels, perhaps the most specialized is the sea otter (Enhydra lutris). The largest of the clan (specimens have weighed as much as 100 pounds and been 5� feet in length), the sea otter occupies the waters along the Pacific shore and is as much at home in the ocean—or as restricted to it—as a seal.
With rear feet which are virtually flippers, a long tapered body and other aquatic adaptations, the sea otter is a powerful and adept swimmer. At top speed it moves through the water at about 5.5 mph. Sea otters have been observed to travel more than 100 yards in a single dive, plunge to depths of 300 feet and submerge for up to four minutes.
Shellfish is the principal food of sea otters. Their strong, very manipulative forepaws, set with partly retractile claws, are well designed for dislodging and dragging shelled creatures out of the sand, rocky crevices and weeds. Their teeth are heavy and flattened for grinding and crushing. Unlike some other marine mammals, the otters do not have blubber to insulate them against the cold water and to serve as an energy storehouse. Instead, the otters have very efficient interior furnaces, a high metabolic rate—nearly five times as rapid as man's—which holds their body temperature at about 100�. To keep themselves stoked up, otters must feed abundantly and as frequently as five times a day. Each day an otter normally consumes about a quarter of its body weight. For an average-sized otter this works out to about 5,000 pounds of seafood platters a year.
The sea otter is one of the few animals with the knack of "tool use." Floating on its back, it will lay a rock on its chest, hold a shellfish in its forepaws and beat it against the rock until the edibles are exposed. The process may be reversed, a rock being used as a hammer to dislodge or split open a shell.
Being relatively long-lived (15-20 years), a dependable breeder (one pup is born every two years but mortality is low because of long and excellent maternal care) and having few natural enemies (in California only sharks), the otters prospered. In prehistoric times they ranged the Pacific coastal waters from Mexico to Alaska and the Aleutian chain, and from the Kurile Islands down to northern Japan and were from 150,000 to 300,000 in number. The otter presumably would have continued to thrive, but about 200 years ago it got caught up in the affairs of modern man.
One of the animal's adaptations to marine life is its coat, an immensely effective layer of deep, soft, insulating fur, composed of a very dense undercoat, three-quarters-of-an-inch thick when fluffed up, topped with longer, sparser guard hairs. (One zoologist has estimated that there are 800 million individual hairs in the pelt of a large adult otter.) While lolling about, otters spend a lot of time grooming their fancy coats, not out of vanity but because if the hair is kept fluffed it retains air and is more buoyant and has better insulating properties. The coat is very roomy, hanging in loose folds. When a pelt is removed it may stretch out to eight feet, or about a third longer than the animal. One reason for this excess of material is that the otter can virtually turn around in its own skin, reaching all parts of it for grooming. Also the folds form a kind of loose pouch across the chest in which the otter can hold shells and rocks. Sea otters are able to remain in water indefinitely, so shedding takes place little by little and the pelt is always prime.
The chief failing of this marvelous coat so far as the otter is concerned is its beauty. The hairs are silvery at the base, becoming dark brown or black toward the tip. The overall effect is of shimmery, deep-piled, luxurious velvet. Ever since man first saw it, he has regarded the sea otter's coat as the finest of all furs. As it has been with other gorgeous natural creations—gemstones, bird plumes, spectacular scenery—so it has been with the otter's pelt. For man it has been only a short step from admiration to avarice—wanting to take the skin off the otter's back and drape it over his own.
Indians along the western coast of North America met the otter early and, predictably coveting the skin, hunted for it. By devious trade routes a few of the pelts reached Chinese markets and impressed buyers there. However, it was not until the mid-18th century, when Russian fur men probed into Aleutian and Alaskan waters, that the otter fur trade to China expanded and a few pelts began to reach Europe, stirring the fancy of the fashionable and the greed of the rapacious. Thereafter, obtaining skins of the otter and the northern fur seal (a more numerous and slightly less desirable furbearer) became a principal motive for the European exploration of the North Pacific. It was also the direct cause of a lot of international squabbles about who owned what (and in consequence the fur resources) in this vast territory. For these reasons, in short order the otter became all but extinct.
Between the mid-18th and early 20th centuries, Russian, American, British, Canadian, Japanese and any other entrepreneurs who could muscle into the territory are thought to have taken about a million otter skins. Many more animals were probably killed, since harvesting methods were wasteful. Then in 1911, in a classic after-the-horse-is-gone move, the marine powers got together and signed an international treaty barring further killing of sea otters on the high seas; in 1913, California and Alaska followed suit and passed laws protecting sea otters in their coastal waters. There were then probably about 2,000 otters remaining in the world. The year before the treaty was signed, a single otter pelt offered on the London fur market fetched $1,703.33.
Following the treaty of 1911 the sea otter entered into its second historic period. It became, along with such creatures as the whooping crane, California condor and black-footed ferret, one of the glamour species of the American conservation movement, the subject of environmental studies and sermons, the object of a lot of attention from public and private wildlife agencies. Eventually it got its very own organization, the Friends of the Sea Otter, perhaps the most ferocious of all single-species protectionist outfits. The animal stirs deep conservationist passions, and what to do about sea otters and who should do things for or to them is currently at the center of a considerable dispute involving private, state and federal wildlife agencies. All in all, the sea otter, in addition to being an interesting creature in itself, is an animal that admirably illustrates a good many of the problems, paradoxes and political realities of the wildlife business in this country.