Coastlines along both sides of the Pacific Ocean


Oceans and rocky shorelines

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? Sea lions and seals are marine mammals, spending a good part of each day in the ocean to find their food. They all 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 all like to eat fish—lots of fish!

So what do you look at to tell “who’s who?” Look at their ears. If you see a small earflap on each side of its head, you are looking at a sea lion. Seals just have a tiny opening for their ears. The sea lion’s earflaps are turned with the opening downward so water does not enter the 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.

Coastal living

Sea lions live along the coastlines and islands of the Pacific Ocean. These fabulously aquatic animals are extremely fit for what might seem like a harsh marine existence to us. A reflective membrane at the back of the eye acts as a mirror, bouncing what little light they light find in the ocean back through the eye a second time. This helps them see underwater, where light may be scarce. Sea lions also rely on excellent senses of hearing and smell.

The front flippers are strong enough to support the animal on land. They also serve to help regulate the sea lion’s body temperature. When it is cold, specially designed blood vessels in the thin-skinned flippers constrict to prevent heat loss, but when it is hot, blood flow is increased to these surface areas to be cooled more quickly. When you see an odd group of dark “fins” sticking out of the water in California harbors, it is usually sea lions sticking their flippers into the air to cool off.

A group of sea lions in the water is called a raft.
Male sea lions don’t eat during the breeding season. They care more about protecting their territory and making sure their females don’t run off with another male.
Sea lions don’t need to drink water—they get all the water they need from the food they eat.
The California sea lion is the sea lion most often seen in animal shows and circuses.
Sea lions often hang out together in large, tight groups, even though there is room to spread out.
Even though they have teeth, sea lions like to swallow their food whole if they can. Their sharp canine teeth are used mostly to protect themselves.
The California sea lion is more slender and more agile on land than other sea lion species.
It is believed that sea lions can see more clearly in water than on land.
The United States Navy uses trained sea lions to help mark and retrieve objects in the ocean as part of the Navy Marine Mammal Program.

Aquatic clowns

The San Diego Zoo has had a variety of sea lion species over the years, but it was California sea lions that played a vital role in the growth and success of the Zoo’s history. Without them, we might not hold the “world-famous” status that we do today. Our Zoo’s founder, Harry Wegeforth, M.D., immediately recognized the popularity of California sea lions among Zoo guests and began working to preserve the public fascination with them.

Because the animals were plentiful off our own coastline, they were collected, brought to the Zoo, and then traded for more exotic species with other zoos around the world. From our member magazine ZOONOOZ, July 1938: “During a recent trip in the East, we had to smile at the amazing popularity of our common California sea lions. Although most zoos exhibited only one or two specimens of these aquatic clowns, the enclosures were always surrounded by laughing faces.”

In 1926, a fierce storm created a flood that washed away the fencing surrounding the Zoo’s sea lion pools. Within minutes, 26 sea lions had been swept away from their Zoo home and onto the streets of downtown San Diego! They were retrieved from the police station, newspaper offices, front porches, and various shops.

As early as 1928, a former circus trainer known as Captain Charles Jensen set up a small stage and trained California sea lions for his weekend shows in the area of the Zoo now known as Raintree Grove, just in front of our current Children’s Zoo. By the time of the 1935 California Pacific International Exposition, he was entertaining capacity crowds with two shows daily. In 1936, Wegeforth Bowl was built to seat 1,500 people. Over the years, it nurtured many real troupers with varied talents, and in 1958 a half-circle pool at the front of the stage was added to show off our sea lions’ swimming skills. The shows included sea lions performing several “tricks,” such as balancing balls or batons on the nose, climbing stairs—even riding a pony!

Today, the Zoo has five sea lion ambassadors who periodically show off their natural talents to the amazement of our guests: Jake was born at the Zoo, Riley was found stranded on the beach and rescued at two days of age, and Baja was born at Six Flags Discovery Kingdom. Three-year-old males Ranger and Maverick were stranded on a beach in San Francisco as pups and came here in 2013. When they arrived, one of our sea lions taught them how to be sea lions, which is very important in their development as they mature. Currently, the sea lions make limited, unscheduled appearances at the 3,000-seat Wegeforth Bowl.

Until recently, sea lions were hunted for their meat, skin, and oil. Some people even used sea lion whiskers for pipe cleaners! Many sea lion populations were wiped out as a result. Steller’s sea lions are endangered, possibly due to the effects of commercial fisheries on their prey species. They were also accidentally killed when caught in commercial fishing nets and were shot on purpose by fishermen who believed the sea lions damage their nets. Protective zones and other measures around known Steller’s sea lion rookeries have been implemented. Other sea lion species are experiencing declines as well, for many of the same reasons. Today, all sea lion species are under the protection of the Marine Mammal Protection Act.

There were over 700 strandings of young sea lions from Washington State to Baja California, Mexico, in 2013, an indication that something unusual is going on in the ocean. Young sea lions typically leave their mother and go out on their own between eight months and one year of age, but if they are weaned early or orphaned, they may not have learned the skills needed to hunt for fish on their own. Scientists are looking at what role pollution may play in these strandings.

A neurotoxin called domoic acid is produced by algae during algae blooms and is called a red tide. Fish eat the algae, and sea lions and other marine animals eat the fish. High levels of domoic acid can lead to lethargy, seizures, and death. And pollution may have a significant role in more of these toxic algae blooms occurring. That’s why it’s so important to keep pollution and trash out of the ocean, and to recycle plastic. There is a correlation between NOT recycling and the emergence of excess domoic acid in marine animals, a documented connection between animal populations and pollution.

You can help all sea lions by keeping plastic items out of our oceans! The plastic rings around six-pack cans can be deadly for sea lions and other marine animals that may swallow them.