Rajidae

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[Classification, Systematics]
Rays found in the waters around Japan are generally classified into eight families: the Pristidae, which have protruding snouts with jagged teeth on both sides, the Rhinobatidae, which have long snouts but no projections on either side, the Platyrhinidae, which have rounded body plates and fine scales all over their bodies, the Rajidae, which have a few scales on their backs and a long, slender tail, the Dasyatidae, which have almost no scales and a venomous stinger on its whip-like tail, the Torpedinidae, which have no scales at all and have an electric organ between their pectoral fins and head, the Myliobatidae, which have large pectoral fins and rounded protruding head tips, and the Mobulidae, which have bat-ear-like fins (cephalic fins) at the end of their heads. Other families found abroad include the freshwater Potamotrygonidae, which are similar to the stingray family, the Anacanthobatidae, whose snouts have filament-like protruding tips, and the Hexatrygonidae, which have six pairs of gill slits.

*Some of the terminology that mentions "Rajidae" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

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［分類，系統］
　日本近海のエイはふつう次の8科に分類される。吻（ふん）が突き出てその両側にぎざぎざのある歯が並ぶノコギリエイ科Pristidae，吻は長いが，両側に突起のないサカタザメ科Rhinobatidae，体板がまるく，体中に細かいうろこのあるウチワザメ科Platyrhinidae，背中に多少のうろこをもち尾部の細長いガンギエイ科Rajidae，うろこがほとんどなくむち状の尾に毒針のあるアカエイ科Dasyatidae，うろこはまったくなく，胸びれと頭の間に発電器官のあるシビレエイ科Torpedinidae，胸びれが大きく，頭の先端がまるく突き出たトビエイ科Myliobatidae，頭の先にコウモリの耳のようなひれ(頭鰭（とうき）)のあるイトマキエイ科Mobulidaeである。このほかアカエイ科に近い淡水産のPotamotrygonidae科，吻端がフィラメント状に突出するAnacanthobatidae科，鰓孔が6対あるHexatrygonidae科が外国に分布する。…

※「Rajidae」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報