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''Raja'' is a genus of skates in the family Rajidae containing nearly 30 species. They are flat-bodied, cartilaginous fish with a rhombic shapes due to their large pectoral fins extending from or nearly from the snouts to the bases of their tails. Their sharp snouts are produced by a cranial projection of rostral cartilage. The mouth and gills are located on underside of the body. They may be either solid-coloured or patterned, and most skates have spiny or thorn-like structures on the upper surface, and some species contain weak electrical organs within their tails. Mating typically occurs in the spring and the female lays numerous eggs per clutch which are encapsulated in leathery cases, commonly known as "mermaid’s purses". Species vary in size. The hedgehog skate (''R. erinacea'') adult length is 50 cm or less. The big skate (''R. binoculata'') may be 2.5 metres long. These bottom-dwellers are active during both day and night, and typically feed on molluscs, crustaceans and fish. Skates are found in most parts of the world, from tropical to near arctic waters, from shallows to depths of more than 2,700 metres. Skates and related species have fossil records dating from the Upper Cretaceous period, thus this well adapted species is quite ancient. ==Species== * ''Raja ackleyi'' Garman, 1881 (ocellate skate) * ''Raja africana'' Capapé, 1977 (African skate) * ''Raja asterias'' Delaroche, 1809 (Mediterranean starry ray) * ''Raja bahamensis'' Bigelow & Schroeder, 1965 (Bahama skate) * ''Raja binoculata'' Girard, 1855 (big skate) * ''Raja brachyura'' Lafont, 1873 (blonde ray) * ''Raja cervigoni'' Bigelow & Schroeder, 1964 (finspot ray) * ''Raja chinensis'' Basilewsky, 1855 * ''Raja clavata'' Linnaeus, 1758 (thornback ray) * ''Raja cortezensis'' McEachran & Miyake, 1988 (Cortez' ray) * ''Raja eglanteria'' L. A. G. Bosc, 1800 (clearnose skate) * ''Raja equatorialis'' D. S. Jordan & Bollman, 1890 (equatorial ray) * ''Raja herwigi'' G. Krefft, 1965 (Cape Verde skate) * ''Raja inornata'' D. S. Jordan & C. H. Gilbert, 1881 (California ray) * ''Raja maderensis'' R. T. Lowe, 1838 (Madeiran ray) * ''Raja microocellata'' Montagu, 1818 (small-eyed ray) * ''Raja miraletus'' Linnaeus, 1758 (brown ray) * ''Raja montagui'' Fowler, 1910 (spotted ray) * ''Raja polystigma'' Regan, 1923 (speckled ray) * ''Raja pulchra'' F. H. Liu, 1932 (mottled skate) * ''Raja radula'' Delaroche, 1809 (rough ray) * ''Raja rhina'' D. S. Jordan & C. H. Gilbert, 1880 (longnose skate) * ''Raja rondeleti'' Bougis, 1959 (Rondelet's ray) * ''Raja rouxi'' Capapé, 1977 * ''Raja stellulata'' D. S. Jordan & C. H. Gilbert, 1880 (starry skate) * ''Raja straeleni'' Poll, 1951 (spotted skate) * ''Raja texana'' A. C. Chandler, 1921 (Roundel skate) * ''Raja undulata'' Lacépède, 1802 (undulate ray) * ''Raja velezi'' Chirichigno F., 1973 (Velez ray) 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「Raja (genus)」の詳細全文を読む スポンサード リンク
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