Otters shed gradually and throughout the year so that they are never without this vital protection. When a sea otter is not grooming, it is either resting or foraging to stoke its blast-furnace metabolism. Adults eat the equivalent of 20 to 25 percent of their body weight daily, which amounts to about 17 pounds of food for an average adult male. Pups must consume about 30 percent of their body weight, which increases rapidly from 4 pounds at birth to 30 pounds by the time they leave their mothers at about 8 months. Their preferred diet includes sea urchins and numerous species of mussels, clams and crabs.
Secondary choices are lobster, snails, octopus, squid, mackerel and sculpin.
Sea otters are known for their use of tools. Characteristically floating on its back at the water's surface, an otter will balance a rock or empty shell on its chest and vigorously hammer a mussel or clam against it to crack open the prey. An otter's front paws, with their connected digits, are more like mitts than hands. But they are extremely sensitive for foraging and dexterous enough to hold food and groom. They are not used for swimming.