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black dogfish
The black dogfish (''Centroscyllium fabricii'') is a species of dogfish shark in the family Etmopteridae. It is common over the outer continental shelf and continental slope at depths of . Females generally inhabit deeper water than males, and depending on the region, smaller sharks may occur at different depths than larger ones. This species is distributed widely in the Atlantic Ocean, from Greenland and Iceland to Virginia and West Africa in the north, and off southwestern Africa and Argentina in the south. The largest member of its family, the black dogfish, typically measures long. It has a stocky, dark brown body that is darker below than above, and bears scattered, minute bioluminescent organs. Its two dorsal fins are preceded by stout spines, and the anal fin is absent.
Active and schooling, the black dogfish is an opportunistic predator and scavenger that mainly consumes bony fishes, crustaceans, and cephalopods. It is aplacental viviparous, with females producing litters of four to 40 pups that are sustained to term by a yolk sac. There is no well-defined breeding season, and mating and birthing take place year-round. The black dogfish contributes significantly to the bycatch of deep-sea commercial fisheries operating in the North Atlantic; it is of little commercial value and is usually discarded. As large portions of its range see little deepwater fishing activity and its northwestern Atlantic population seems to be stable, the International Union for Conservation of Nature has listed this species under Least Concern overall. It has been assessed as Near Threatened in the northeastern Atlantic, where its numbers may have declined from heavy fishing pressure.
== Taxonomy and phylogeny ==
The first known specimen of the black dogfish was collected near Julianehåb in Greenland and described by Danish zoologist Johannes Reinhardt in his 1825 ''Ichthyologiske bidrag''. Reinhardt gave it the name ''Spinax fabricii'' in honor of missionary and naturalist Otto Fabricius, who pioneered the study of Greenlandic fishes.〔 German biologists Johannes Müller and Jakob Henle, in their 1839–41 ''Systematische Beschreibung der Plagiostomen'', created the new genus ''Centroscyllium'' for this species.〔〔
According to the IUCN, further taxonomic investigation is required to confirm the black dogfish in the North Atlantic and the southeastern Atlantic represent the same species.〔 A 2010 phylogenetic study by Nicolas Straube and colleagues, based on nuclear and mitochondrial DNA, found the black dogfish is the sister species of the whitefin dogfish (''C. ritteri''), and the two are, in turn, sister to the clade formed by the granular dogfish (''C. granulatum'') and combtooth dogfish (''C. nigrum'').〔
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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