Sea Otter

Enhydra lutris
Family: Mustelidae
sea otter

Photo © Kate Wynne


See a 3-D animation of a sea otter skull.

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sea otter range map

Distribution/Migration: North Pacific. Alaska population ranges from Aleutians to Prince William Sound and Southeast Alaska. Non-migratory but move in response to prey abundance. Purple shows year-round range.

This web page is modified from the book Marine Mammals of Alaska by Kate Wynne, illustrated by Pieter Folkens, available at the Alaska Sea Grant Bookstore.

Marine Mammal Guide

SIZE: Average adult male 5 ft (1.5 m), 70 lbs. Average adult female 4 ft (1.2 m), 60 lbs. At birth 10 in (0.3 m), 5 lbs.

BODY: Largest member of the weasel family, smallest marine mammal. Long, flat tail and webbed hind feet. Retractable claws on front paws. Head round with small eyes, triangular nose, and visible ear pinnae. Densest fur of any mammal (no blubber).

COLOR: Body dark brown to blond with lighter head. Head and neck lighten with age until white in old animals.

BEHAVIOR: Usually swim on back with feet in the air but may swim on stomach, porpoise, and roll repeatedly while traveling. Groom fur frequently. Eat only while floating. Groom, rest, and nurse young while floating or hauled out on rocky shores or sandbars. Front paws used for foraging and grooming but not swimming. Form sex-segregated groups. Hundreds may float together in "raft" while resting. Short and shallow divers, usually <100 ft for 1–2 min.

HABITAT: Coastal. Shallow waters with rocky or sandy substrate.

FOOD HABITS: Eat primarily benthic invertebrates: clams, mussels, urchins, crabs, fish. Capable of dramatically affecting size and abundance of prey.

LIFE HISTORY: Sexually mature at 3–6 yrs. Peak breeding September–October in Alaska. Single pup per 1+ yrs after variable gestation of 5–8 mos. In Alaska, most pups are born in May (on land or water) and are dependent on mother for 5–12 mos.

STATUS AND HUMAN INTERACTIONS: Approx 80,000 in Alaska waters. Numbers increasing in Southeast and Southcentral Alaska, but listed as threatened in Southwest Alaska due to drastic declines in the Aleutians. Subsistence and handicraft use of pelts by Alaska Natives. Vulnerable to oil contamination and boat strikes. Known to compete with shellfisheries and to entangle in coastal gillnets.