Raja (genus)
Raja Temporal range: 70–0Ma Maastrichtian to Present | |
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Raja brachyura | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Rajiformes |
Family: | Rajidae |
Genus: | Raja Linnaeus, 1758 |
Species | |
29, see text. |
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)
See also
- List of prehistoric cartilaginous fish
References
- Froese, Rainer, and Daniel Pauly, eds. (2005). "Rajidae" in FishBase. August 2005 version.
- "skate." Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 08 Dec. 2009 <http://www.britannica.com/EBchecked/topic/547322/skate>.
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