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The sea otter can be found in coastal areas throughout the North Pacific.

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Floating on its back in groups called “rafts,” the sea otter sometimes holds paws with other sea otters to stay together.

Scientific name: Enhydra lutris
Average weight: 40 kg (male)
30 kg (female)
Average length: 1.5 m (male)
1.4 m (female)
Average lifespan: 10–15 years (male)
15–20 years (female)
A sea otter pauses on some logs.

About

Biology

The sea otter is the smallest marine mammal in the world yet the largest of the otters. While most marine animals have blubber to keep them warm in icy ocean waters, the sea otter relies, instead, on its fur coat for protection. It has the thickest pelt in the animal kingdom. The coat of an adult contains between 800 million and one billion tightly packed hairs. It has long, reddish brown guard hairs on top and a soft, dense insulating under layer. The hairs also have a protective coating of oil, making the sea otter’s fur waterproof. In fact, the sea otter’s skin never gets wet.

Unfortunately, humans also found value in the otter’s lustrous, thick fur. The sea otter was nearly hunted to extinction in the early 20th century. Currently, oil spills are the greatest threat to the otter, as the oil can destroy the natural insulating properties of the otter’s remarkable fur.

The sea otter’s strong, rudder-like tail and large, webbed hind feet help propel it through the water. When it swims underwater, its nostrils close to prevent water from entering. The river otter, weasel and badger are all relatives of the sea otter.

Habitat and behaviour

The sea otter prefers to live close to shore in waters with rocky or soft ocean bottoms and rarely comes onto land. It mates, grooms, hunts, eats and sleeps in the ocean. And its large, complex kidneys even allow it to drink saltwater. The otter commonly floats on its back, using its underbelly as a table while eating. Sea otters often float together in a group called a  “raft.” The rafts are gender-specific, and the large number of otters in them serves as protection against attack from predators such as the bald eagle and the shark.

A carnivore, the sea otter has a high metabolic rate and consumes as much as 30 percent of its body weight a day. The otter is an excellent swimmer and can dive up to 75 metres to retrieve food, which includes slow-moving fish, mussels, abalones, snails, crabs, octopus and sea urchins. An average dive, however, is about 30 metres. The otter relies on its sense of touch with its sensitive paws to find food on the ocean floor. It is one of the few mammals in the world that uses tools to feed, often cracking open the shells of crustaceans with a rock to get at the tasty morsels inside.

A large portion of the sea otter’s time and energy is devoted to grooming, since it is dependent on its fur for warmth. Grooming involves rubbing, rolling, licking and blowing air into the fur to keep the hairs separate and prevent mats from forming, which can block the flow of heat.

Range

Although the sea otter population was greatly reduced by overhunting at the turn of the last century, the otter is now legally protected and can be found in coastal areas throughout the North Pacific, especially in Alaska. The species was slowly reintroduced in the late 1960s and early 1970s from Alaska to British Columbia, and the province is now home to approximately 3,500 to 4,000 sea otters.