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Japanese angelshark
The Japanese angelshark (''Squatina japonica'') is a species of angel shark, family Squatinidae, found in the northwestern Pacific Ocean off China, Japan, and Korea. It is a bottom-dwelling shark found in sandy habitats down to deep. This species has the flattened shape with wing-like pectoral and pelvic fins typical of its family, and grows to or more in length. Its two dorsal fins are placed behind the pelvic fins, and a row of large thorns occurs along its dorsal midline. Its upper surface is cryptically patterned, with numerous squarish dark spots on a brown background.
Feeding on fishes, cephalopods, and crustaceans, the Japanese angelshark is a nocturnal ambush predator that spends most of the day lying still on the sea floor. This species gives birth to live young, which are sustained during gestation by yolk. The litter size varies from two to 10. The Japanese angelshark is not dangerous to humans unless provoked. It is fished in large numbers and used for meat and shagreen, a type of leather. The International Union for Conservation of Nature has listed it under Vulnerable, citing the intense bottom trawling activity within its range and the low resilience of angel sharks to fishing pressure.
==Taxonomy and phylogeny==
The Japanese angelshark was described by Dutch ichthyologist Pieter Bleeker in an 1858 volume of the scientific journal ''Acta Societatis Scientiarum Indo-Neerlandicae''. The type specimen is a male long, collected off Nagasaki, Japan, hence the specific epithet ''japonica''.〔〔 Other common names for this species include change angel shark, change canopy shark, Japanese angelfish, and Japanese monkfish.〔
Using mitochondrial DNA, a 2010 phylogenetic analysis reported that the Japanese angelshark forms a clade with the other Asian angelsharks included in the study: the ocellated angelshark (''S. tergocellatoides'') and the sister species pair of the Taiwan angelshark (''S. formosa'') and the Indonesian angelshark (''S. legnota''). These Asian species are, in turn, allied with European and North African angel shark species. Molecular clock estimation suggested the Japanese angelshark lineage diverged from the rest of the Asian angelsharks some 100 million years ago during the Cretaceous.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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