HABITAT AND DISTRIBUTION
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.
APPEARANCE
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.
BEHAVIOR
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.
BREEDING
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.
ECOLOGY
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.
CONSERVATION
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.
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