The Sea Otter’ 
By Kari W. KENYON 
United Siates Fish and Wildlife Service 
[With 6 plates] 
IN GENERAL FORM the sea otter “nhydra lutris resembles the weasel 
and river otter, of which animals it is a large relative. The male 
attains a weight of 85 pounds, the female about 65 pounds; the young 
at birth weigh from 3 to 5 pounds. It is peculiar among members of 
its family, the Mustelidae, in having deserted dry land and fresh 
water to take up a marine life. Among marine mammals it is pecu- 
liar in its adaptation to the sea. It does not possess an insulating 
layer of blubber but is protected from the chill of North Pacific 
waters by a blanket of air trapped among the fine and closely packed 
fibers of its inch-long delicate fur. Unlike the river otter and fur 
seal, the sea otter has but little protective coating of guard hair. 
The fine guard hairs present add to its beauty but do not offer much 
protection to the soft underfur. Unlike other marine mammals, the 
sea otter has never taken to the open sea. It usually feeds in shallow 
water from 5 to 50 feet in depth. Its food consists primarily of 
such sedentary forms as sea urchins, rock oysters, mussels, a variety 
of snail-like mollusks and, in California, abalones. Occasionally 
fish and octopus are eaten. 
Although the sea otter is not ideally adapted to its marine environ- 
ment, it is far more at ease in the water than ashore. The flipper- 
like hind feet are clumsy on land and the long flexible body, some- 
what like a liquid-filled bag, is poorly suited to walking. When otters 
haul out to sleep or preen, they seldom venture more than a few feet 
from the water. 
Otters come ashore in greatest numbers when storm waves make 
food diving difficult. When the weather is calm they usually sleep 
on the surface of the sea, simply pulling a strand of kelp over their 
bodies, resting the head on the chest and placing their forepaws over 
their eyes. But often in the Aleutians during calm summer weather, 
1Printed by permission of The Fauna Preservation Society, with some revision, from 
Oryx, vol. 4, No. 3, November 1957. 
399 
