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The Pacific angelshark (''Squatina californica'') is a species of angel shark, family Squatinidae, found in the eastern Pacific Ocean from Alaska to the Gulf of California, and from Ecuador to Chile, although those in the Gulf of California and southeastern Pacific may in fact be separate species. The Pacific angelshark inhabits shallow, coastal waters on sandy flats, usually near rocky reefs, kelp forests, or other underwater features. This species resembles other angel sharks in appearance, with a flattened body and greatly enlarged pectoral and pelvic fins. Characteristic features of this shark include a pair of cone-shaped barbels on its snout, angular pectoral fins, and a brown or gray dorsal coloration with many small dark markings. It attains a maximum length of . An ambush predator, the Pacific angelshark conceals itself on the sea floor and waits for approaching prey, primarily bony fishes and squid. Prey are targeted visually and, with a quick upward thrust of the head, snatched in protrusible jaws. Individual sharks actively choose ideal ambush sites, where they stay for several days before moving on to a new one. This species is more active at night than during the day, when it stays buried in sediment and seldom moves. Reproduction is viviparous, with the embryos hatching inside the mother's uterus and being sustained by a yolk sac until birth. Females give birth to an average of six young every spring. Pacific angelsharks are not dangerous to humans unless provoked, in which case their bite can cause a painful injury. They are valued for their meat and are captured by commercial and recreational fishers across their range. A targeted gillnet fishery for this species began off Santa Barbara, California in 1976 and ended in 1994, after overfishing and new regulations led to its near-collapse. This species is now mainly fished in Mexican waters. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened, as the Californian population is largely protected and recovering, while the impact of Mexican fisheries is unknown. ==Taxonomy and phylogeny== The Pacific angelshark was first scientifically described in 1859 by William Orville Ayres, the first Curator of Ichthyology at the California Academy of Sciences.〔Bester, C. (Biological Profiles: Pacific Angelshark ). Florida Museum of Natural History Ichthyology Department. Retrieved on June 22, 2009.〕 He gave it the specific epithet ''californica'', as the originally-described specimen was caught off San Francisco. Locally, this species may also be referred to as angel shark, California angel shark, or monkfish. The Chilean angelshark (''Squatina armata'') of the southeastern Pacific was synonymized with this species by Kato, Springer and Wagner in 1967, but was later tentatively recognized as a separate species again by Leonard Compagno.〔 The taxonomic status of angel sharks in the southeastern Pacific – whether they are ''S. californica'', ''S. armata'', or if there is more than one ''Squatina'' species in the region – remains unresolved. The angel sharks inhabiting the Gulf of California may also represent a different species, as they mature at a much smaller size than those from the rest of their range. |2=''Squatina armata'' }} }} }} A phylogenetic study based on mitochondrial DNA, published by Björn Stelbrink and colleagues in 2010, reported that the sister species of the Pacific angelshark is the sand devil (''S. dumeril'') of the western North Atlantic. The two species are estimated to have diverged approximately 6.1 Ma, close to when the Isthmus of Panama first began to form. The authors also found that Pacific angelsharks from the Gulf of California differed genetically from those elsewhere, though they were equivocal as to whether this represented a species-level distinction. 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「Pacific angelshark」の詳細全文を読む スポンサード リンク
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