Dasyatidae
by J. D. McEachran and C. Capape
Medium to large rays (disc width to 2.1 m), the disc rhomboid to oval, its width ranging from greater to less than its length; snout obtuse and little produced to acute and moderately produced, head not elevated from disc; tail distinct from disc, slender and whip-like, equal to or much longer than distance from snout to cloaca, with one or several serrated spines on top near base, keels or membranous folds along upper or lower sides (or both) present in some species. Nostrils separated from mouth, but front margins greatly expanded to reach back and join each other. Mouth almost straight or arched, with a transverse row of bulbous papillae along floor, teeth small and numerous. Spiracles well developed, without tentacle-like processes. Dorsal and caudal fins absent, pectoral fins joined to side of head, the finrays beginning at tip of snout. Upper surfaces naked or covered with tubercles, thorns or thornlets.
Benthic on soft bottoms, generally in shallow tropical and warm temperate waters, but also to depths of 200 m; mostly marine, although often entering estuaries, but some tropical species restricted to freshwater (South America, Africa, south-eastern Asia), and one species epipelagic in oceanic waters and worldwide (Dasyatis violacea). Rather inactive (except D. violacea), generally resting on the bottom partially covered with sand or mud, or slowly swimming over the bottom by undulating the pectoral fins; common in tropical inshore waters, where commonly marketed, the serrated spines (removed on capture) occasionally used as spear tips, daggers, awls or needles. Feeding on fishes, crustaceans, molluscs and polychaetes. Ovoviviparous; females contain 2-9 embryos, with a gestation period of up to a year. Living or fresh specimens should be handled with great care since the spine on the tail can inflict a nasty wound, into which poison is injected.
Genera 5 (up to 12 according to some authors); in Clofnam area 3.
Recent revisions: on a regional basis only, Fowler (1941), Bigelow and Schroeder (1953).