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Manta rays are large rays belonging to the genus ''Manta''. The larger species, ''M. birostris'', reaches in width while the smaller, ''M. alfredi'', reaches . Both have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Elasmobranchii (sharks and rays) and are placed in the family Myliobatidae (eagle rays). Mantas are found in temperate, subtropical and tropical waters. Both species are pelagic; ''M. birostris'' migrates across open oceans, singly or in groups, while ''M. alfredi'' tends to be resident and coastal. They are filter feeders and eat large quantities of zooplankton, which they swallow with their open mouths as they swim. Gestation lasts over a year, producing live pups. Mantas may visit cleaning stations for the removal of parasites. Like whales, they breach, for unknown reasons. Both species are listed as vulnerable by the International Union for Conservation of Nature. Anthropogenic threats include pollution, entanglement in fishing nets, and direct harvesting for their gill rakers for use in Chinese medicine. Their slow reproductive rate exacerbates these threats. They are protected in international waters by the Convention on Migratory Species of Wild Animals, but are more vulnerable closer to shore. Areas where mantas congregate are popular with tourists. Only a few aquariums are large enough to house them. In general, these large fish are seldom seen and difficult to study. ==Taxonomy and etymology== }} }} }} }} }} }} }} }} }} |caption=Phylogeny of stingrays (Myliobatiformes)〔 }} The name "manta" is Portuguese and Spanish for mantle (cloak or blanket), a type of blanket-shaped trap traditionally used to catch rays. Mantas are known as "devilfish" because of their horn-shaped cephalic fins, which are imagined to give them an "evil" appearance. Manta rays are members of Chondrichthyes, fish with tough cartilage rather than bone in their skeletons. Mantas are among the Elasmobranchii (sharks and rays), in the superorder Batoidea (rays and skates) and the order Myliobatiformes (stingrays and relatives).〔 The genus ''Manta'' is part of the eagle ray family Myliobatidae, where it is grouped in the subfamily Mobulinae along with the devil rays. Mantas evolved from bottom-dwelling stingrays, eventually developing more wing-like pectoral fins. ''M. birostris'' still has a vestigial remnant of a sting barb in the form of a caudal spine.〔 The mouths of most rays lie on the underside of the head, while in mantas they are right at the front. Manta rays and devil rays are the only ray species that have evolved into filter feeders. The scientific naming of mantas has had a convoluted history, during which several names were used for both the genus (''Ceratoptera'', ''Brachioptilon'' ''Daemomanta'' and ''Diabolicthys'') and species (such as ''vampyrus'', ''americana'', ''johnii'' and ''hamiltoni''). All were eventually treated as synonyms of the single species ''Manta birostris''.〔〔〔(【引用サイトリンク】publisher=California Academy of Sciences ) Check genus and type "Manta" in search box.〕 The genus name ''Manta'' was first published in 1829 by Dr Edward Nathaniel Bancroft of Jamaica.〔; see E.N. Bancroft ''On the fish known in Jamaica as the sea-devil'', 1829〕 The specific name '' birostris'' is ascribed to Johann Julius Walbaum (1792) by some authorities and to Johann August Donndorff (1798) by others.〔 The name ''alfredi'' was first used by Australian zoologist Gerard Krefft, who named the manta after Prince Alfred.〔(【引用サイトリンク】title=Manta )〕 Authorities were still not in agreement and some argued that the black color morph was a different species from the mostly white morph. This proposal was discounted by a 2001 study of the mitochondrial DNA of both. A 2009 study analyzed the differences in morphology, including color, meristic variation, spine, dermal denticles (tooth-like scales) and teeth of different populations. Two distinct species emerged: the smaller ''M. alfredi'' found in the Indo-Pacific and tropical east Atlantic, and the larger ''M. birostris'' found throughout tropical, subtropical and warm temperate oceans. The former is more coastal〔 while the latter is more ocean-going and migratory.〔 A third possible species, preliminarily called ''Manta sp. cf. birostris'', reaches at least in width, and inhabits the tropical west Atlantic, including the Caribbean. It and ''M. birostris'' occur in sympatry.〔 A 2010 study on mantas around Japan confirmed the morphological and genetic differences between ''M. birostris'' and ''M. alfredi''. 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「Manta ray」の詳細全文を読む スポンサード リンク
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