The scientific name for sea otters is Enhydra lutris, which means “otter in the water.” The name fits sea otters well because they spend almost all of their time in the ocean—they eat, sleep, mate, give birth, and feed their young at sea. Although there are 12 species of otters, there is only one species of sea otters, divided into two subspecies. Sea otters are the largest members of the weasel family (which includes weasels, skunks, minks, sables, ermines, wolverines, and badgers), and they are also the smallest of all marine mammals.
For its size, a sea otter’s lungs are twice as large as those of other mammals. Large lungs give sea otters more oxygen for diving—and even help them to float better. Sea otters have strong jawbones and large, rounded teeth to help them crush the shells of crabs, snails, and sea urchins. Their big lower teeth, called incisors, jut forward and are used to scoop the meat out of the shells. When swimming in murky water, sea otters use their sensitive whiskers to feel their way around and to find food. Their whiskers also help sea otters feel vibrations in the water.
Sea otters eat many different types of food—and a lot of it! Shellfish is their favorite food, especially clams, scallops, mussels, and abalone. But they also like crabs, sea urchins, squid, snails, octopus, and fish. They prefer foods that they can pick up easily or pry off rocks. To collect and eat their food, sea otters often use large stones as tools. Humans, a few other primates, and sea otters are the only mammals known to use tools. They use stones as hammers to break loose abalone or mussels from the rocks. They also bang shellfish against flat stones to crack open their hard shells.
Sea otter pups are born on land and in the water. They weigh four to five pounds at birth. For the first month of its life, a sea otter pup rests quietly on its mother’s chest as she cuddles, grooms, and feeds it. Until the pup is six months old, its mother never leaves it except to look for food. When she does, she sometimes wraps the pup in kelp to keep it from drifting away on an ocean current. To escape from danger, a sea otter mother tucks her pup under her foreleg and dives underwater.
Sea otters are found only in the North Pacific Ocean, where they live along rocky shorelines and in sheltered coves. Although their range was once wider, today sea otters can only be found along the coasts of Russia, Alaska, and central California.
Northern sea otters off the coast of Alaska and Russia are living in healthy numbers. But the population of the Southern sea otter, from the Central Coast of California, has declined by about 12% since 1995. At present, no one knows for sure what is causing the decline. Biologists suggest that there may be an ecological imbalance in the sea otter’s habitat. Like all animals, sea otters have a role in maintaining balance in the natural world.