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Dimorphism

Male and female California Sea Lion

The California sea lion (Zalophus californianus) is a coastal eared seal native to western North America. It is one of six species of sea lion. Its natural habitat ranges from southeast Alaska to central Mexico, including the Gulf of California. Sea lions are sexually dimorphic; males are larger than females, and have a thicker neck, and protruding sagittal crest. They mainly haul-out on sandy or rocky beaches, but they also frequent manmade environments such as marinas and wharves. Sea lions feed on a number of species of fish and squid, and are preyed on by killer whales and sharks.

California sea lions have a polygynous breeding pattern. From May to August, males establish territories and try to attract females with which to mate. Females are free to move in between territories, and are not coerced by males. Mothers nurse their pups in between foraging trips. Sea lions communicate with numerous vocalizations, notably with barks and mother-pup contact calls. Outside their breeding season, sea lions spend much of their time at sea, but they come to shore to molt.

Sea lions are particularly intelligent, can be trained to perform various tasks and display limited fear of humans if accustomed to them. Because of this, California sea lions are a popular choice for public display in zoos, circuses and oceanariums, and are trained by the United States Navy for certain military operations. The International Union for Conservation of Nature (IUCN) lists the species as Least Concern due to its abundance. Predation by California sea lions on threatened or endangered salmon species at Bonneville Dam has resulted in more than 50 of them being killed by state officials.

Diet Edit

California sea lions feed on a wide variety of seafood, mainly squid and fish, and sometimes clams. Commonly eaten fish and squid species include salmon, hake, Pacific whiting, anchovy, herring, rockfish, lamprey, dogfish, and market squid.[22] They mostly forage near mainland coastlines, the continental shelf, and seamounts. They may also search along the ocean bottom.[8] California sea lions may eat alone or in small to large groups, depending on the amount of food available. They sometimes cooperate with other predators, such as dolphins, porpoises, and seabirds, when hunting large schools of fish.[23] Sea lions sometimes follow dolphins and exploit their hunting efforts.[4]Adult females feed between 10–100 km (6.2–62.1 mi) from shore.[13] Males may forage as far as 450 km (280 mi) from shore when water temperatures rise.[24] They also have learned to feed on steelhead and salmon below fish ladders at Bonneville Dam and at other locations where fish must queue in order to pass through dams and locks that block their passage.

Range Edit

British Columbia to Gulf of California coastline

Amazing Adaptations Edit

Sea lions have outstanding adaptations for living both on land and in the sea.

A Nose that Closes Edit

A sea lion closes its nostrils to keep out of the water, and opens them to breathe when it surfaces.

Ability to Stay Underwater Edit

When a sea lion dives, its heartbeat slows and blood is restricted to its most vital organs, allowing it to dive hundreds of feet and stay underwater up to 10 minutes.

Seeing in the Dark Edit

A sea lion’s eyes capture enough light to see in deep, dark water.

Shaped for Swimming Edit

The sea lion’s torpedo-shaped body and amazing agility allows them to swim with ease, catch fish and escape predators.

Blubber for Warmth Edit

A thick layer of blubber helps sea lions stay warm in cold water. Sea lions eat more fish in the winter to build up their blubber layers. In the summer, their appetites reduce and they use up the extra blubber layer.

Flippers for Movement Edit

A sea lion can turn its hind flippers forward to help them walk on land.

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