Mature males protect large territories, encompassing the territories of several females. On the outskirts of the range are rafts of bachelor males, too young or too old to hold their own territories. A sea otter's normal body temperature is about 100 F, while the ocean is a chilly 35 to 60 F. Sea otters carefully groom their fur to trap a layer of insulating air bubbles between their warm skin and the icy water. But even that fur can't stop the loss of body heat. Sea otters have to stay active to stay warm.
Sea otters find prey along rocky shores, on sandy seafloors and in sloughs and estuaries.
In California, sea otters are closely associated with the kelp forest. Many kinds of prey live on and among the kelp, and the otters often wrap themselves in kelp strands to stay close to their favorite feeding grounds. Sea otters actually help the kelp forest to thrive by eating sea urchins. In southern California, where sea otters have not made a comeback, sea urchins can get so numerous that they nibble the kelp forest down to stubs. This is less likely to happen where otters are part of the ecosystem.