Biology Reference
In-Depth Information
log, or blown-down tree. The young wolverines are independent by fall, and disperse to seek their own
territories.
While there is concern that the remnant wolverine populations in the lower forty-eight states may
be disappearing, the wolverine seems to be thriving, at least for the present, in the vast reaches of the
far north. It is a fascinating and unusual creature that deserves far more study and attention than it has
heretofore received.
THE SEA OTTER
Largest of the weasel family in North America, the sea otter
(Enhydra lutris)
has gone the river otter
one better and become, for all practical purposes, a fully aquatic marine mammal. Although sea otters
occasionally come on land for brief periods, such as waiting out severe storms or to bask on the rocks,
most of their lives are spent completely in and under the waters of the North Pacific.
Hunted relentlessly for their valuable fur, sea otters were brought to the edge of extinction, and at
one time only about two thousand remained throughout their entire range. Now, after years of full pro-
tection, there are probably 150,000 to 200,000 of them—a remarkable comeback.
Like river otters, sea otters are much loved by everyone—well, almost everyone; Alaska crab fisher-
men and California abalone and sea urchin fishermen tend to loathe sea otters with a passion. Accord-
ing to sea otter expert David Garshelis, groups of otters, known as pods, can indeed severely deplete
local crab populations, at least temporarily, in Alaskan waters.
Jack Ames of the California Fish and Game Department believes that sea otters were historically in
balance with abalone, sea urchins, and other species on which the otters feed. Then, when the sea ot-
ters were virtually wiped out 150 or more years ago, the population of abalone, sea urchins, and other
creatures prized by humans as food grew rapidly. Soon a thriving commercial fishery grew up around
these species and came to be regarded as “traditional.”
With the return of sea otters in substantial numbers during the second half of this century, the old
balance between predator and prey, which didn't include commercial fishing by humans, was reestab-
lished. As Ames says, a commercial abalone fishery simply can't exist in the presence of sea otters.
Sea otters commonly weigh up to eighty or eighty-five pounds, and a few specimens have reached
one hundred pounds. Lacking the seal's insulating layer of blubber, sea otters survive the cold ocean
water by virtue of the densest fur of any animal—100,000 hairs per square centimeter!
Nor is this extraordinarily warm, thick coat the sea otter's only adaptation for marine life. Very large
lungs serve a dual function: they allow for extended time underwater, and they also permit the sea otter
to float effortlessly on the surface. Indeed, sea otters actually sleep while floating on their backs.
