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| regnum = Animalia | phylum = Chordata | classis = Chondrichthyes | subclassis = Elasmobranchii | ordo = Myliobatiformes | subordo = Myliobatoidei | subdivision_ranks = Families | subdivision = *Hexatrygonidae *Plesiobatidae *Urolophidae *Urotrygonidae *Dasyatidae *Potamotrygonidae *Gymnuridae *Myliobatidae }} Stingrays are a group of rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae (deep water stingray), Urolophidae (stingarees), Urotrygonidae (round rays), Dasyatidae (whiptail stingrays), Potamotrygonidae (river stingrays), Gymnuridae (butterfly rays), and Myliobatidae (eagle rays). Most stingrays have one or more barbed stingers (modified from dermal denticles) on the tail, which are used exclusively in self-defense. The stinger may reach a length of approximately , and its underside has two grooves with venom glands.〔(【引用サイトリンク】 Dangerous and Venomous Aquarium Fish )〕 The stinger is covered with a thin layer of skin, the integumentary sheath, in which the venom is concentrated. A few members of the suborder, such as the manta and porcupine rays, do not have stingers. Stingrays are common in coastal tropical and subtropical marine waters throughout the world. Some species, such as ''Dasyatis thetidis'', are found in warmer temperate oceans, and others, such as ''Plesiobatis daviesi'', are found in the deep ocean. The river stingrays, and a number of whiptail stingrays (such as the Niger stingray), are restricted to fresh water. Most myliobatoids are demersal (inhabiting the next-to-lowest zone in the water column); but some, such as the pelagic stingray and the eagle rays, are pelagic.〔(【引用サイトリンク】 Pelagic Stingray )〕 While most stingrays are relatively widespread and not currently threatened, for several species (for example ''Taeniura meyeni'', ''D. colarensis'', ''D. garouaensis'', and ''D. laosensis''), conservation status is more problematic, leading to their being listed as vulnerable or endangered by IUCN. The status of several other species are poorly known, leading to their being listed as Data Deficient.〔(【引用サイトリンク】 IUCN Red List )〕 ==Behavior== The flattened bodies of stingrays allow them to effectively conceal themselves in their environment. Stingrays do this by agitating the sand and hiding beneath it. Because their eyes are on top of their bodies and their mouths on the undersides, stingrays cannot see their prey; instead, they use smell and electroreceptors (ampullae of Lorenzini) similar to those of sharks.〔(Stingray behavior? ). Scubaboard.com. Retrieved on 2012-07-17.〕 Stingrays feed primarily on molluscs, crustaceans, and occasionally on small fish. Some stingrays' mouths contain two powerful, shell-crushing plates, while other species only have sucking mouthparts. Stingrays settle on the bottom while feeding, often leaving only their eyes and tail visible. Coral reefs are favorite feeding grounds and are usually shared with sharks during high tide.〔(Stingray City – Altering Stingray Behavior & Physiology? ). Divephotoguide.com (2009-04-14). Retrieved on 2012-07-17.〕 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「Stingray」の詳細全文を読む スポンサード リンク
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