Raja (genus)

Raja is a genus of skates in the family Rajidae containing nearly 30 species. Formerly a wastebasket genus, many species historically placed here have been moved to other genera in the family, such as Amblyraja, Beringraja, Dipturus and Leucoraja. Raja 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, ranging from about 35 to 180 cm (1.1–5.9 ft) in length. 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. They are mainly found from shallows to a depth of 500 m (1,600 ft), but some occur deeper and R. inornata down to 1,600 m (5,200 ft). Skates and related species have fossil records dating from the Upper Cretaceous period, thus this well adapted species is quite ancient.