http://www.montereybayaquarium.org/animals-and-experiences/exhibits/sea-otters

The sea otter is a marine mammal. They are the second smallest marine animal and in the weasel family. They live their life mostly in water and dive for their food. They are also one of the few kinds of mammals that use tools to use for food like prying open clam shells. They eat urchins, abalone, mussels, clams, crabs, and snails. They live off the coast of northern and eastern North Pacific Ocean. Sea otters do not have thick blubber to keep them warm. They have the worlds thickest, heaviest fur and this keeps them warm. They have up to a million hairs per inch. Sea otters live in groups called "rafts". Their groups are very close with each other. When otters sleep, they sleep side by side with strands of kelp around them so they don't drift far away from each other. Sea otters play an important role in the ecosystem.

Sources: Montereybayaquarium.org and Defenders.org