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The California sea lion (''Zalophus californianus'') is a coastal eared seal native to western North America. It is one of five 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 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 Orcas and white sharks. California sea lions have a polygynous breeding pattern. From May to August, males establish territories and try to attract females to mate with. 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 of 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.〔(【引用サイトリンク】publisher=Oregon Department of Fish and Wildlife )〕 ==Taxonomy== The California sea lion was described by René Primevère Lesson, a French naturalist, in 1828. It is grouped with other sea lions and fur seals in the family Otariidae. Otariids, also known as eared seals, differ from true seals in having external ear flaps, and proportionately larger foreflippers and pectoral muscles. Along with the Galapagos sea lion and the extinct Japanese sea lion, the California sea lion belongs to the genus ''Zalophus'', which derives from the Greek words ''za'', meaning "intensive," and ''lophus,'' meaning "crest." This refers to the protruding sagittal crest of the males, which distinguishes members of the genus. Traditionally, the Galapagos sea lion and Japanese sea lion were classified as subspecies of the California sea lion. However, a genetic study in 2007 found that all three are in fact separate species. The lineages of the California and Japanese sea lion appear to have split off 2.2 million years ago during the Pliocene. The California sea lion differs from the Galapagos sea lion in its greater sexual dimorphism.〔 The Steller sea lion is the closest extant relative of the ''Zalophus'' sea lions, being a sister taxon.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「California sea lion」の詳細全文を読む スポンサード リンク
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