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The pelagic stingray (''Pteroplatytrygon violacea'') is a species of stingray in the family Dasyatidae, and the sole member of its genus. It is characterized by the wedge-like shape of its pectoral fin disc, which is much wider than long, as well as by the pointed teeth in both sexes, whip-like tail with extremely long tail spine, and uniform violet to blue-green coloration. It generally reaches in width. The pelagic stingray has a worldwide distribution in waters warmer than , and migrates seasonally to spend the summer closer to the continental shelf and at higher latitudes. The only stingray that almost exclusively inhabits the open ocean, this species is typically found in surface waters down to a depth of . As a consequence of its midwater habits, its swimming style has evolved to feature more of a flapping motion of the pectoral fins, as opposed to the disc margin undulations used by other, bottom-dwelling stingrays. The diet of the pelagic stingray consists of free-swimming invertebrates and bony fishes. It is an active hunter, using its pectoral fins to trap and move food to its mouth, and has been known to take advantage of seasonal feeding opportunities such as spawning squid. Like other stingrays, it is aplacental viviparous, meaning that the embryos are sustained initially by yolk and later by histotroph ("uterine milk"). With a short gestation period of 2–4 months, females may bear two litters of 4–13 pups per year. Birthing generally occurs in warm water near the equator, with the exception of the Mediterranean Sea, with the timing varying between regions. Rarely encountered except by fishery workers, the pelagic stingray can inflict a severe, even fatal wound with its tail spine. This species is caught as bycatch throughout its range; it is of little economic value and usually discarded, often with high mortality. However, there is evidence that its numbers are increasing, perhaps owing to the heavy fishing of its natural predators and competitors (e.g., sharks). Along with the pelagic stingray's global distribution and prolific life history, this has led the International Union for Conservation of Nature (IUCN) to assess it as of Least Concern. ==Taxonomy and phylogeny== The pelagic stingray was originally described by French naturalist Charles Lucien Bonaparte in the 1832 third volume of ''Iconografia della fauna italica per le quattro classi degli animali vertebrati''. He named it ''Trygon violacea'', from the Latin ''viola'' ("purple"), and designated two specimens collected off Italy as the species syntypes.〔〔 The genus ''Trygon'' has since been synonymized with ''Dasyatis''. In 1910, American zoologist Henry Weed Fowler placed the pelagic stingray in the newly created subgenus ''Pteroplatytrygon'', from the Greek ''pteron'' ("fin"), ''platus'' ("broad"), and ''trygon'' ("stingray").〔 Later authors elevated ''Pterplatytrygon'' to the rank of full genus, though some taxonomists dispute whether this species is distinct enough to warrant separation from ''Dasyatis''.〔〔 }} }} }} }} Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology, found that the pelagic stingray is one of the more basal members of its family, being the sister taxon to a clade that contains ''Pastinachus'', ''Dasyatis'', and Indo-Pacific ''Himantura'' species.〔 Other common names for the pelagic stingray include the blue stingray and the violet stingray.〔 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「pelagic stingray」の詳細全文を読む スポンサード リンク
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