Mammals: Sea Lion

Sea lions and seals—what’s
the difference?

Sea lions, seals, and walruses are in a scientific group of animals called Pinnipeds, which means "wing foot" or "feather foot." You could probably pick out a walrus if you saw one, but how do you tell sea lions and seals apart? Both are marine mammals, spending a good part of each day in the ocean to find their food. They both have flippers at the end of their limbs to help them swim. Like all marine mammals they have a thick layer of blubber to keep them warm in the chilly ocean. And they both like to eat fish—lots of fish! So what do you look at to tell who’s who? Their ears. If you see a small ear flap on each side of its head, you are looking at a sea lion. Seals just have a tiny opening for their ears. Sea lions are also able to rotate their hind flippers forward to help them scoot along beaches and rocky shorelines. Seals cannot do this, and must wriggle, hunch, roll, or slide to get around out of the water.

Life in a harem

Male sea lions, called bulls, are several times larger that the adult females, called cows. During the breeding season, each adult bull tries to gather up as many cows as he can to form his "harem." Sea lion harems, or family groups, can number up to 15 cows and their young. The bull watches over his harem, protecting it from harm. But don’t think the harem has the place all to itself—popular resting spots can support dozens of harems. A large group of sea lions gathered together on land or floating ice is called a colony. During the birthing season these areas are known as rookeries.

These lions can roar!

Never timid about speaking what’s on their minds, sea lions make all sorts of barks, honks, trumpets, and roars. During the breeding season, bulls bark loudly and continuously to establish or defend their territories. A baby sea lion, called a pup, can pick out its mother from among hundreds gathered on rocky shores just by the sound she makes. Between the bulls roaring, the mothers barking, and the pups bleating, the rookery is a noisy place indeed!

What’s up, pup?

Pups are born on land, with their eyes open and their tummies ready for some of their mother's rich milk. The milk is high in fat, and this helps the pup grow that important layer of blubber to keep warm. At just a few weeks of age sea lion pups are ready for their first swimming and fishing lessons. They also must learn how to stay away from sharks and how to survive storms at sea!

Dive, dive!

A sea lion’s sleek body is perfect for diving deep in the ocean (up to 600 feet, or 180 meters) in search of tasty fish and squid. Because sea lions are mammals and must breathe air, they can’t stay underwater forever! But with the help of nostrils that seal up automatically when they dive, a sea lion can remain submerged for up to 40 minutes at a time. Sea lions are great swimmers, too, and can reach speeds of up to 25 miles per hour (40 kilometers per hour) for short bursts. This helps them escape from their enemies: killer whales and sharks.

Whiskers are wonderful

It can be pretty dark in the ocean, but sea lions can find their way around with the help of their sensitive whiskers. Each long whisker, called a vibrissa, is loosely attached to the sea lion’s upper lip. Like a straw in a soda bottle, each whisker can rotate around with the underwater currents, letting the sea lion "feel" any food swimming nearby.

Sea lions are carnivores. They eat fish, squid, crabs, and clams. Steller sea lions Eumetopias jubatus also eat seals. Most of the sea lion's food is just swallowed whole. The sea lion will toss the fish or squid up and around until it can slide headfirst down the sea lion’s mouth. They use their flat back teeth to crush food with a hard shell before swallowing. At the San Diego Zoo, sea lions are fed five different types of fish: capelin, squid, pompano, mackerel, and herring.

Clever critters

Why are sea lions often seen in shows at zoos, marine parks, and circuses? Because they are intelligent animals that can be taught to perform many of their natural behaviors on cue. Clever sea lions have delighted people with their abilities for decades.

Sea lion status

Until recently, sea lions were hunted for their skin and oil. Some people even used sea lion whiskers for pipe cleaners! Many populations of sea lions were wiped out. In some areas, sea lions are shot by fishermen who blame them for damaging their nets. With the help of international laws to protect them, some sea lion populations have made a comeback.