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| regnum = Animalia | phylum = Chordata | classis = Chondrichthyes | subclassis = Elasmobranchii | superordo = Batoidea | subdivision_ranks = Orders | subdivision = * Torpediniformes * Pristiformes * Rajiformes * Myliobatiformes }} Batoidea is a superorder of cartilaginous fish commonly known as stingrays or rays, but it also includes the skates and sawfishes. Approximately 560 species are described in thirteen families. Batoids are in the fish subclass Elasmobranchii along with sharks, as they are closely related. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral surfaces. ==Anatomy== Batoids are flat-bodied, and, like sharks, are cartilaginous marine fish, meaning they have a boneless skeleton made of a tough, elastic substance. Most batoids have five ventral slot-like body openings called gill slits that lead from the gills, but the Hexatrygonidae have six. Batoid gill slits lie under the pectoral fins on the underside, whereas a shark's are on the sides of the head. Most batoids have a flat, disk-like body, with the exception of the guitarfishes and sawfishes, while most sharks have a streamlined body. Many species of batoid have developed their pectoral fins into broad flat wing-like appendages. The anal fin is absent. The eyes and spiracles are located on top of the head. Batoids have a ventrally located mouth and can considerably protrude their upper jaw (palatoquadrate cartilage) away from the cranium to capture prey.〔.〕 The jaws have euhyostylic type suspension, which relies completely on the hyomandibular cartilages for support.〔.〕 Bottom-dwelling batoids breathe by taking water in through the spiracles, rather than through the mouth as most fishes do, and passing it outward through the gills. 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「batoidea」の詳細全文を読む スポンサード リンク
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