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| • | Pups weigh about 13 pounds when born | |
| • | Females weigh about 200-400 pounds | |
| • | Males can grow to 400-850 pounds | |
| • | Can dive up to 900 feet | |
| • | Can hold their breath for up to 10 minutes | |
| • | Can swim up to 25 MPH | |
| • | Molt once a year | |
Who Are
These Big “Dogs”?
California sea lions first appeared
in the fossil record about 120,000 to 220,000 years ago. Today,
they are known for their intelligence, playfulness, and noisy barking.
Their color ranges from chocolate brown in males to a lighter,
golden brown in females. Males may reach 850 lbs. and seven feet
in length. Females grow to around 200-400 lbs. and up to six feet
in length.
Sea lions have a "dog-like" face, and at around five
years of age, males develop a bony bump on top of their skull called
a sagittal crest. These members of the Otariidae or walking seal
family have external ear flaps and large flippers that they use
to "walk" on land. The trained "seals" in zoos
and aquariums are usually California sea lions.
California sea lions are found from Vancouver Island, British Columbia
to the southern tip of Baja California in Mexico. They breed mainly
on offshore islands, ranging from southern California's Channel
Islands south to Mexico, although a few pups have been born on
Año Nuevo and the Farallon Islands in central California.
There is a distinct population of California sea lions at the Galapagos
Islands. A third population in the Sea of Japan became extinct,
probably during World War II.
Sea
Lions Are Adapted To Live On Land & In The Sea
Sea lions are adapted for movement on land as well
as in the water. Wing-like front flippers have a bone structure
similar to that in our arms and hands. Swimming with these flippers
propels the sea lion forward, while the hind flippers steer. Both
pairs of flippers enable a sea lion to walk on land. California
sea lions are very social animals, and groups often rest closely
packed together at favored haul-out sites on land called colonies,
or float together on the ocean's surface in "rafts." They
are sometimes seen porpoising, or jumping out of the water, presumably
to speed up their swimming. Sea lions have also been seen "surfing" breaking
waves.
| Kalika, one of our females, posing for the camera |
California sea lions are opportunistic eaters,
feeding on prey such as squid, octopus, herring, rockfish, mackerel,
and small sharks. In turn, sea lions are preyed upon by Orcas
(killer whales) and great white sharks.
Most pups are born in June or July and weigh 13-20 lbs. They nurse
for at least five to six months and sometimes over a year. Mothers
recognize pups on crowded rookeries through smell, sight, and vocalizations.
Pups also learn to recognize the vocalizations of their mothers.
Breeding takes place a few weeks after birth. Males patrol territories
and bark almost continuously during the breeding season.
There’s A Lot
To Learn From Pinnipeds
Scientists study Pinnipeds to learn about their natural history,
reproduction, and behavior. The information helps when scientists
try to save species that are endangered.
| Kim Terrell with Murray, our only male Sea Lion |
Most studies observe Pinnipeds when they’re on land while
pupping, breeding, or molting. Little is known about pinniped behavior
at sea including diving, migrating, habitat use, feeding strategies,
and social interactions.
Scientists are now using compact satellite transmitters to track
seal movements. With this new technology, scientists can virtually
dive and swim with seals. Some scientists use a small computer
call a time-depth recorder or TDR. The TDR is temporarily glued
to the back of the pinniped and eventually falls off then the animal
comes ashore later in the year to molt. The TDR records the time
and depth measurements and stores the data until it is transmitted
to a satellite. The satellite calculates the animal’s position
and then sends the data to the laboratory for analysis.
Scientists at National Geographic have designed Crittercams. Safely
worn by wildlife, Crittercams capture video, sound, and other information,
giving us rare views of the private lives of animals. By allowing
us this animal’s-eye view, Crittercams help to solve scientific
mysteries. What we learn from Crittercams helps us protect the
very animals that wear them.
How
have people affected sea lions?
More than 7,000 years ago,
California sea lions were hunted by the Chumash and Nicoleño
Indians on the Channel Islands for subsistence. In the late 1800s
they were hunted commercially for their hides. The impact of harvesting
on sea lion populations has never been clear.
Since the Marine Mammal Protection Act was passed in 1972, the
sea lion population has grown at a healthy increase of 10% each
year. However, California sea lions continue to be shot by fishermen
over competition for fish, particularly salmon. California sea
lions often are seen in salmon spawning grounds, but in some cases,
eat more lampreys than salmon. Lampreys (a type of fish) are parasites
of salmon.
Pesticides and heavy metals in the ocean may impact sea lions.
In one study, the tissues of females that had aborted pups had
much higher concentrations of DDT than females who carried their
pups to term.
Marine debris is a threat to sea lions. They can become entangled
in nylon fishing nets or plastic packaging materials, causing severe
injury or drowning. Sea lions also ingest plastic debris, which
can cause obstructions in the digestive tract. Keeping our seas
and beaches clean has a huge impact on the health of not just sea
lions but all marine life.
Feeding wild marine animals has led to numerous problems, including
millions of dollars of damages to docks and boats caused by the
animals looking for more handouts. Though tempting to approach
a sea lion, remember that these are wild animals and a safe distance
protects both you and the animal from harm.
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