Roughtail Stingray

The roughtail stingray has a diamond-shaped pectoral fin disk 1.2–1.3 times as wide as long, with straight to gently sinuous margins, rather angular outer corners, and a moderately long, obtuse snout. The eyes are proportionally smaller than other stingrays in its range and immediately followed by larger spiracles. There is a curtain of skin between the nostrils with a finely fringed posterior margin. The mouth is bow-shaped with a row of six papillae (nipple-like structures) across the floor. The seven upper and 12–14 lower tooth rows at the center are functional, though the total number of tooth rows is much greater. The teeth are arranged with a quincunx pattern into flattened surfaces; each has a tetragonal base with a blunt crown in juveniles and females, and a pointed cusp in adult males. The pelvic fins have nearly straight margins and angular tips. The tail is long and whip-like, measuring some 2.5 times the length of the disc. A long, saw-toothed spine is placed atop the tail at around half a disc length back from the tail base; sometimes one or two replacement spines are also present in front of the existing one. Behind the spine, there is a long ventral fin fold that is much lower than that of the southern stingray. Individuals under 46–48 cm (18–19 in) across have completely smooth skin. …

The roughtail stingray is broadly but discontinuously distributed in the coastal waters of the western Atlantic Ocean. It occurs from the Georges Bank off Cape Cod, Massachusetts following warm ocean waters southward to Florida, the Bahamas, and the northeastern Gulf of Mexico; there are also scattered reports from Venezuela to Argentina and on the Barrier reef in Belize. A single record from Kollam, India was likely a misidentification. One of the deepest-diving stingrays, the roughtail stingray has been recorded to a depth of 274 m (899 ft) in the Bahamas. However, it is most common at a depth of 15–50 m (49–164 ft). This bottom-dwelling species favors live-bottom habitat (patches of rough terrain that are densely encrusted by sessile invertebrates), and also frequents adjacent open areas of sand or mud. Rays in the northwestern Atlantic do not usually enter brackish water. The favored temperature range of the roughtail stingray is 15–22 °C (59–72 °F), which is the most important factor determining its distribution. It conducts seasonal migrations off the eastern United States: from December to May, this ray is found over the middle and outer parts of the continental shelf from Cape Hatteras in North Carolina to Florida, with larger rays occurring further south than smaller ones. …

The roughtail stingray is reportedly not highly active, spending much time buried in the sediment. It is a generalist predator whose diet generally reflects the most available prey in its environment. It mainly captures prey off the bottom, but also opportunistically takes free-swimming prey. A variety of invertebrates, as well as bony fishes such as sand lance and scup, are known to be consumed. Off Massachusetts, the main prey are crabs (Cancer), bivalves (Mya), gastropods (Polinices), squid (Loligo) and annelid worms. In Delaware Bay, most of its diet consists of the sand shrimp Crangon septemspinosa and the blood worm Glycera dibranchiata; the overall dietary composition there is nearly identical to that of bluntnose stingrays (Hypanus say) that share the bay. The shrimp Upogebia affinis is a major food source off Virginia. Off Florida, crustaceans (Rananoides, Ovalipes, Sicyonia brevirostris, and Portunus) and polychaete worms are the most important prey. Sharks and other large fishes, in particular the great hammerhead (Sphyrna mokarran), prey upon the roughtail stingray. The live sharksucker (Echeneis naucrates) is sometimes found attached to its body. …