Sea otter Biology

The sea otter is the smallest marine mammal on the coast of British Columbia . Males can weigh up to 45 kilograms and reach 148 centimeters in length. Females are slightly smaller. Sea otters have the thickest fur of any living animal: 100,000 or more hairs per square centimeter or about 1,000,000 hairs per square inch. Unlike whales and seals, who rely on their thick layers of blubber to insulate themselves in cold waters, the blubberless sea otters rely only on their fur for insulation. To maintain body warmth, sea otters feed constantly, and continually groom their fur; clean fur allows air to be trapped and warmed between the strands, and prevents water from touching the animals' skin. Soiled and clumped fur, in contrast, leads to a loss of insulation and threatens the sea otter with hypothermia.

Life History

Female sea otters begin to have pups when they are between 3 and 5 years of age. Males do not breed until they are at least 5 or 6 years old. Females generally bear one pup a year, with most births occurring in the spring. Pups remain with their mothers for at least the first 6 to 8 months of life. Sea otter females, on average, live from 15 to 20 years, and male sea otters live from 10 to 15 years.

Habitat

Sea otters live in unpolluted nearshore marine environments, usually in depths under 40 meters. On the west coast of Vancouver Island, sea otters have been observed to frequent different habitats in different seasons more sheltered waters during winter storms, for example. They are social animals, congregating in single-sex (all males or all females) groups called rafts. Rafts of sea otters can contain hundreds of animals. Males and females tend to occupy different territories. Males generally expand into new areas first, while females use areas that sea otters have occupied for longer periods of time and expand into areas vacated by male groups. In Alaska, male sea otters have been known to travel as much as 100 km. a day. The sea otter has only a few natural predators besides man. Bald eagles are known to prey on pups, and killer whales eat sea otters, usually when other preferred foods are not available.