Sea Otters Photos (Enhydra
lutris)
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The Sea Otter
In 1742, Vitus Bering's men returned with
sea otter pelts from the historic voyage of discovery of
Alaska. Interest in these rich furs initiated an era of
exploitation which almost wiped out the sea otter. © Patrick J. Endres
The sea otter (Enhydra lutris) lives in shallow water areas
along the shores of the North Pacific. Its range once extended
from southern California north then west through the Aleutian
Islands, to the Kamchatka Peninsula, and south to the northern
islands of Japan.
General description
The hind feet are webbed and are adapted for swimming. The toes on the forefeet are short and stiff, enabling the animal to deftly handle food. © Patrick J. Endres
Sea otters are members of the weasel family (Mustelidae)
and are related to mink and river otters. Adult males weight
70 to 90 pounds (32-41 kg) with some individuals weighing
100 pounds. Females average 40 to 60 pounds (18-27 kg).
Adults reach a length of 4.5 feet (1.4 m). On land their gait is clumsy. Probably because
of this vulnerability, they are seldom found more than a
few yards from water.
Older animals often develop a silvery head. This, combined with the prominent whiskers, leads to the nickname of "Old Man of the Sea." © Patrick J. Endres
The fur, which is possibly the finest in the world, consists
of a very dense underfur of inch-long fibers and sparse
guard hairs. The underfur ranges from brown to almost black.
Guard hairs may be black, pale brown, or silver, often giving
a veiled effect of silvery hairs on a dark background.
Unlike seals, which rely on a heavy layer of blubber for
protection against the cold North Pacific waters, sea otters
depend on air trapped in their fur for maintaining body
temperature. If the fur becomes soiled or matted by material
such as oil, the insulation qualities are lost. This results
in loss of body heat and eventual death. For this reason,
otters spend much time grooming their fur to keep it clean.
Life history
A pup weighs 3 to 5 pounds (1.4-2.3 kg) at birth and is light brown in color. The female's maternal instinct is very strong and she seldom leaves her pup except when diving for food. When traveling, sleeping, or preening, the pup usually rides its mother's chest as she floats on her back. © Patrick J. Endres
Sea otters mate at all times of the year, and young may
be born in any season. However, in Alaska most pups are
born in late spring. Like other marine mammals, they have
only one pup during each breeding cycle. The pup may
weigh 30 pounds (14 kg) when weaned and looks almost as
big as its mother. Females can produce one pup a year, but
in areas where food is limited, they may produce pups every
other year.
Se otters are gregarious and may become concentrated in an area, sometimes resting in pods of fewer than 10 to more than 1,000 animals. © Patrick J. Endres
Sea otters usually do not migrate. They seldom travel far
unless an area has become overpopulated and food is scarce.
Breeding males will drive nonbreeding males
out of areas where females are concentrated. In some areas,
the nonbreeding males will concentrate in "male areas"
which are usually off exposed points of land where shallow
water extends offshore. Bald eagles prey on newborn pups
and killer whales may take a few adults, but predation is
probably insignificant. Many sea otters live for 15 to 20
years.
Food habits
In the wild, sea otters never eat on land. © Patrick J. Endres
Sea urchins, crabs, clams, mussels, octopus, other marine
invertebrates, and fishes make up the normal diet of sea
otters. They usually dive to the bottom in 5 to 250 feet
of water and return with several pieces of food, roll on
their backs, place the food on their chests and eat it piece
by piece using their forepaws and sometimes a rock to crack
shells.
The search for food is one of the most important daily activities of sea otters, as large amounts are required to sustain the animal in healthy condition. © Patrick J. Endres
Feeding dives
generally last less than one minute although some otters
are capable of staying underwater for five minutes or more.
Captive animals require a daily food intake equal to one-quarter
of their body weight. In order to obtain the 8 to 15 pounds
(4-7 kg) of solid food needed, an otter may have to bring
up 40 to 50 pounds (18-23 kg) of whole shellfish. Their
feeling habits may result in conflicts with subsistence,
recreational, and commercial fishers when otters move into
areas that support important shellfish resources.
Text: Karl Schneider, Revised and reprinted 1994, adapted
from ADF&G Wildlife Notebook Series:
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