Unlike seals and sea lions, sea otters do not have a layer of blubber under their skin. It uses its front paws for grasping and holding, as do some otters that live in fresh water. For information about freshwater otters, see the article on Otter . Sea otters may eat as much as a fifth of their body weight every day. They feed on abalones, clams, crabs, fish, mussels, octopuses, sea urchins, and squids.
Sea otters pry open shellfish in various ways.
They use their teeth or their paws, and may pound one clam or mussel against another. A sea otter also may balance a rock on its belly and hammer the shellfish against it. For centuries, sea otters have been hunted for their valuable fur. From the mid-1700's through the 1800's, fur traders killed so many sea otters that the animal almost disappeared. In 1911, Canada, Japan, Russia, and the United States signed a treaty that prohibited the hunting of sea otters.