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Sealions belong to the order of mammals called Pinnipeds, which means "flipper-foot" and includes seals and walruses. Although excellent swimmers, well-adapted to life at sea, they remain dependent on land to breed.

Two species of pinnipeds are found in the Galapagos: the California sea lion (Zalophus californianus), featured on this page, and the Galapagos fur seal. The California sea lion is the most abundant large mammal in the Galapagos. The population is presently about 50,000. This number varies substantially, especially during El Niño episodes, when fish supplies dwindle. The Galapagos population is considered a subspecies (wollebacki) of the California sea lion, which aside from being slightly smaller it resembles in most respects.

The sea lions of the Galapagos compel visitors' attention more than any other animal. They're the largest animal in in the islands (bulls weigh 500 pounds or more) and usually the first one to be encountered on beaches where most excursions begin.

They're almost oblivious to human presence, although they might raise an eyelid as you walk past. During the breeding season, males can be rather aggressive, as they defend territories against all-comers, people included. The females may be defensive of young, but the pups are curious and wriggle towards people to smell the strangers. On land, even the big males can be easily outpaced, but under the waves, snorkelers are treated to evocative displays of grace and power. They can stay submerged upto half an hour, and can dive down to 500 feet. When they return to the surface, they breathe by lying their head sideways and breathing through the side of the mouth.

During the breeding season, males vigorously defend territories, comprised of a stretch of beach, preferably with plenty of females, perhaps as many as 30. As there are many more bulls than territories most males (the smaller and weaker ones) forgo territories unless at the peak of strength. This ensures only the strongest, biggest males get to breed. The female reproductive cycle enables them to maximize the chances of successfully raising young. They can delay implantation of a fertilized egg, which remains in stasis until environmental conditions (mainly food availability) are more suitable. Then the embryo implants in the uterine wall and gestation occurs normally. After implantation, gestation takes about nine months­the same as people. Following birth, a pup is weaned within a year, but in years of low food availability this may extend up to three years.

Sealions feed almost exclusively on fish, which they chase or ambush. The sea lion's agility and bursts of speed make it a formidable predator. It eats small fishes such as sardines, which have been found in stomach contents left on a beach. They may take larger species also.

Predators include bull sharks and in the western islands, orcas. Starvation is the main cause of mortality, especially during El Niño years. When nursing mothers are in danger of starving, pups are abandoned. This is sad to see but it does ensure that the mothers who have reached adulthood will survive to try again in a better year.

The outlook for the Galapagos sea lion is quite favorable, given its relatively large population size. Human threats include illegal fishing of its prey species and being caught in fishing gear.


Sea Lion Monitoring and Conservation (CDRS)
California Sea Lion (International Marine Mammal Association)
Zalophus wollebaeki (Galapagos sea lion: OBIS-SEAMAP

Mostly images
Sea lion underwater
Photos of Zalophus californianus wollebacki
Sea lion — Espanola Island

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sealion underwater photo sealion yawning photo

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