Otters are semiaquatic animals. They are graceful swimmers with lithe, cylindrical bodies, short limbs, webbed feet, and a tapering tail.
Some otters swim and live near freshwater, others swim and live only near oceans. Some otters are at home in both habitats.
Otters are underwater hunters. They use their tails and hind feet to swim rapidly, twisting and turning as they chase their prey. When diving they can close their ears and nostrils.
They locate their prey, such as fish, frogs, crustaceans, and waterbirds, by sight and with their stiff highly sensitive whiskers.
The sea otter lives and feeds in the ocean and rarely comes ashore. It has thick fur that keeps it warm in the cold waters of the ocean. All otters have outer and inner fur; the outer fur forms spiky clumps when the otter comes out of the water, enabling the water to run off easily.
The sea other is one of a few mammals that can manipulate tools. It uses stones to crack open shellfish. It places the stone on its chest and then smashes its prey against the stone to break open the shell. Otters will keep the stone in a fold in the skin where it is ready for use at any time.
The sea otter, Enhydra lutris, lives in the North Pacific. The North American river otter, Lontra canadensis, lives in rivers and near lakes in North America. The Eurasian river otter, Lutra lutra, lives in both rivers and coastal habitats in Europe. The Asian small-clawed otter, Aonyx cinerea, lives in wetlands in India and Southeast Asia.