Which marine mammal is the only living species in the genus Enhydra?

The sea otter is the only living species in the genus Enhydra. Its scientific name is Enhydra lutris, and it is a marine mammal in the weasel family, Mustelidae.

Sea otters are unusual mustelids because they can spend their entire lives in the ocean. They do not rely on blubber for insulation; instead, they have exceptionally dense fur that traps air and is often described as the densest fur of any animal. Constant grooming is essential because dirty or matted fur loses its insulating ability.

The genus Enhydra once included extinct relatives, including Enhydra macrodonta. Fossil evidence suggests the lineage became isolated in the North Pacific about 2 million years ago, while sea otters diverged from other otters roughly 5 million years ago. Sea otters are also ecological keystone species: by eating sea urchins, they can help protect kelp forests. They are sometimes confused with seals or similar-looking river otters, but their taxonomy, dense fur, webbed hind feet, and marine lifestyle set them apart.