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Onefin electric ray
The onefin electric ray or Cape numbfish (''Narke capensis'') is a common but little-known species of electric ray in the family Narkidae, native to South Africa and Namibia. It is a benthic fish found in shallow coastal bays over sandy or muddy bottoms. This small species reaches in length, and has a nearly circular pectoral fin disc and a short, muscular tail that supports a large caudal fin. It can be identified by its single dorsal fin, which is located over the large pelvic fins. Its dorsal coloration is yellowish to dusky brown.
Like other members of its family, the onefin electric ray can defend itself with a strong electric shock produced from a pair of kidney-shaped electric organs beside its head. It feeds mainly on polychaete worms, and likely gives birth to live young. The International Union for Conservation of Nature (IUCN) presently lacks enough information to assess the conservation status of this species. It is often caught incidentally by bottom trawl fisheries off South Africa, and may also be impacted by pollution from coastal development.
==Taxonomy==
The onefin electric ray was described by German naturalist Johann Friedrich Gmelin in 1789, in the 13th edition of ''Systema Naturae''.〔 Gmelin's name for the species was printed as ''Raja capensis'' in some copies of the book, and as ''Raja rapensis'' in others. The original spelling was probably ''rapensis'', which modern taxonomists regard as a typesetting error as the etymology of ''capensis'' ("of the Cape (Good Hope )") is far more reasonable. Later sources have consistently used ''capensis'', though to officially fix the specific epithet under that spelling would require a decision by the International Commission on Zoological Nomenclature (ICZN).〔〔 Gmelin did not refer to any type specimens.〔 In 1826, German naturalist Johann Jakob Kaup created the new genus ''Narke'' for this species, separating it from the other electric rays known at the time on the basis of its curved back and single dorsal fin.〔 Later, more species were assigned to ''Narke''.〔
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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