The American Round Stingray Family – Urotrygonidae
The fish of the American Round Stingray or Urotrygonidae Family are a group of marine fish found in shallow waters of tropical and warm temperate areas of the Atlantic and Pacific Oceans. There are forty global family members in three genera that are known in Mexico as rayas redondas Americanas. Of these, nine are found in Mexican waters, one in the Atlantic and eight in the Pacific.
The American Round Stingrays have round bodies featuring a very sturdy tail, which ends in a true caudal fin. This well-developed caudal fin, whose length is approximately equal to the disc length, has one or occasionally two large venomous spines. They lack a dorsal fin. They are small (16 cm; 6.3 inches) to moderately sized (80 cm; 31 inches) and differ from other traditional stingrays largely by the length and shape of their tails. They have flattened discs that are up to 1.3 times longer that they are deep. Their snouts are rounded, varying from angular to pointed, and their eyes and spiracles are found on top of their heads. Their nostrils, mouths, and gill slits are on their undersides. They have small teeth. Their pectoral fins are found in one continuous circle around the sides of their heads. The skin on their dorsal sides may be smooth or covered with denticles and thorns.
The American Round Stingrays vary in color from tan to brown or gray. These colors are displayed in varying pattern shades from plain to spotted or mottled, which give them a dappled appearance. Their undersides are a uniform white or light yellow color. They are well camouflaged when viewed from either above or below. They are normally found over and within sandy or muddy bottoms from the intertidal zone to depths of approximately 50 feet. During breeding season, they can be found in great numbers at the mouths of estuaries and in shallow bays. They are good swimmers, propelling themselves by their oversized pectoral fins, and are capable of substantial bursts of speed. They are normally buried in mud or sand covered Substrate, leaving only the eyes and spiracles exposed to await their prey. They are non-aggressive toward humans but their large venomous barbed stinger (2.5 cm; 1 inch) embedded on top of the middle of the tail can inflict major pain to humans who enter the ocean as waders or swimmers.
The American Round Stingrays are diurnal feeders and rely on sight and smell to locate prey. They use their mouths and large fins to remove bottom sediment and expose buried food. Their diet consists primarily of bottom dwelling invertebrates such as worms, shrimp, amphipods, clams and other small mollusks, and small fish. In turn they are preyed upon by the Northern Elephant Seal and larger fish such as the Giant Sea Bass and sharks including the Leopard Shark.
Reproduction in American Round Stingrays occurs via internal fertilization. Embryos develop by aplacental viviparity with a gestation period of three months. Babies are born live with litter sizes ranging from one to six. Larger females produce the largest litters. They are miniature adults that are independent from birth. The discs of newborns vary in width from 6.3 cm (2.5 inches) to 8.0 cm (3.1 inches). Their lifespan ranges from ten to twelve years.
From a fishing perspective, the American Round Stingrays are a common catch and normally a “catch and release” as they are not viewed as suitable for human consumption. Caution: Rays of the Urobatis Genus and Urotrygon Genus have tails with a very venomous spine. These rays are potentially dangerous as they can inflict wounds with intense pain and slow recovery. Approximately 1,500 stings from stingrays are reported annually.
There are eight members of the American Round Stingray or Urotrygonidae Family, one from the Atlantic and seven from the Pacific, currently presented in this website:
Blotched Stingray, Urotrygon chilensis
Cortez Stingray, Urobatis maculatus
Panamic Stingray, Urotrygon aspidura
Reef Stingray, Urobatis concentricus
Round Stingray, Urobatis halleri
Spiny Stingray, Urotrygon munda
Thorny Stingray, Urotrygon rogersi
Yellow Stingray, Urobatis jamaicensis