Dasyatis centroura
Rough-tailed
(Also: Rough-tailed northern stingray; Rough-tailed stingray; Roughtail stingray; clam cracker; stingaree)

Roughtail stingrays, Dasyatis centroura, reside in tropical and temperate waters of the coastal Atlantic Ocean, ranging from the coast of Massachusetts to Brazil, the Mediterranean Sea, the Bay of Biscay, and Angola. During summer months, roughtail stingrays are more prevalent in bays, estuaries and coastal waters. From December to May, they tend to migrate to northern waters away from the coast but not beyond the continental shelf. (Mitchill, 2008)

Roughtail stingrays usually reside in benthic environments and in marine and brackish waters. They prefer areas with sandy bottoms. In the summer, they favor bays, estuaries, and coastal waters, and in winter, they move away from the coast but not beyond the continental shelf. They generally swim at depths of 50 to 200 m, but they have been seen at depths of 274 m in the Bahamas. In the eastern Atlantic Ocean, roughtail stingrays remain near shore and are found at an average depth of 60 m, while rays in the western Atlantic are found deeper at 200 m. (MacEachran, 2004)

Male roughtail stingrays have an average width of 1.5 m while females have an average width of 1.6 m. Their disc length can be as long as 2.2 m. The body of roughtail stingrays is diamond-shaped, and a long tail trails from their backside. Their whiplike tail has many rows of venomous barbs and can grow up to 2.5 times the length of the body. Body color ranges from dark brown to an olive tone. The underside is white, while the tail is black. The outer edges of their disc bear distinctive conical tubercles. Roughtail stingrays do not have a dorsal finfold, and their snout is fairly long and angular. They can weigh as much as 300 kg. (Capape, 1993; Mitchill, 2008)

Rays in the family Dasyatidae, including roughtail stingrays, produce relatively few young. Stingrays in general have 1 litter a year, producing between 2 and 6 young. Embryos developing in their mother's womb receive most of their nutriment from the histotroph, a milky substance secreted by the mother’s uterine lining. Embryos absorb nutriment through their skin and spiracles. During this time, embryos absorb the yolk sack and stalk. Roughtail stingrays are born fully developed and relatively large (up to half the size of a full grown adult), increasing their chances of survival. (Capape, 1993; The IUCN Red List of Threatened Species, 2010; Weinheimer and Jonna, 2003)

Little is known about the natural mating behavior and mating system of roughtail stingrays. They, like other stingrays, do not form monogamous pairs, and they may be polygynous like southern sting rays (Dasyatis americana). Rays practice internal fertilization; a male inserts one of his two claspers into the female’s cloaca to deposit sperm. (Weinheimer and Jonna, 2003)

Male roughtail stingrays reach sexual maturity at a length of 130 to 150 cm and females at 140 to 160 cm. In females ready to reproduce, their left ovary is commonly more developed than the right. Roughtail stingrays generally breed in Autumn or early winter. Gestation lasts 4 months, and females usually give birth in April. Stingrays have one litter a year, producing between 2 and 6 young. Roughtail stingrays measure between 34 at 37 cm at birth. (Ribeiro-Prado and Amorim, 2008; The IUCN Red List of Threatened Species, 2010; Weinheimer and Jonna, 2003)

Pregnant female roughtail stingrays provide nutritional support to their developing offspring. While young are in the embryonic sac, their stomachs and intestine develop first. This helps them to digest the milky fluid (histotroph) secreted by their mother's uterus. After birth, young rays receive no further investment from their mother and are able to find food on their own. (Weinheimer and Jonna, 2003)

Little information is known regarding the lifespan and longevity of roughtail stingrays. Some sharks and rays do not reach full maturity for 20 to 30 years. Large rays live about 70 years, some living for more than 100 years. (Weinheimer and Jonna, 2003)

Rays, including roughtail stingrays, spend most of their time partially buried in sand in shallow warm waters. Rays often migrate vast distances, often in large groups. (Dulcic, et al., 2003; Weinheimer and Jonna, 2003)

LIttle information is available regarding the home range of roughtail stingrays.

Roughtail stingrays use touch, taste, sight, hearing, and smell to perceive their enviornment. Furthermore, like other cartilaginous fish, they can detect electical waves produced by other organisms. They use this ability to find infaunal prey buried within the substrate.

Roughtail stingrays are opportunistic carnivores, adapting their diet to include the most available prey. Crustaceans, such as vernal crabs Liocarcinus vernalis and callianassid shrimp Upogebia affinis, are an integral part of their diet. Stomach content analyses indicate that roughtail stingrays eat cephalopods such as squid Loligo and cuttlefish Sepia latimanus. Other prey include bony fishes, like sand lance Ammodytes dubius and scup Stenotomus chrysops. Infaunal polychaete worms (Glycera dibranchiata) are also consumed. (Ribeiro-Prado and Amorim, 2008)

Sharks are the main predators of stingrays, including rougtail stingrays. To avoid visual detection, rays conceal themselves just below the surface of muddy and sandy bottoms. Their barbed spine serves as a defense against certain predators; however, it is not always successful, as stingray spines are found in the mouths of many types of sharks. Great hammerhead sharks have a unique method of eating rays: they pin down a ray to the seafloor using their uniquely shaped head, then pivot around to bite the ray's disc. Some humans also eat roughtail stingrays. (Grey, et al., 2006)

Rays, such as roughtail stingrays, are avid hunters of benthic mollusks, fish, crustaceans and worms, and they may help regulate infaunal benthic community structure. Rays are also prey for sharks, such as great hammerhead sharks. (Chisholm, et al., 2004)

Roughtail stingrays are commonly eaten by Australian Aborigines. The Aborigines use stingray spines to make spears tips, daggers, and whips. Rays are also consumed in Europe and Asia, and the fins of some rays are harvested in Asia for traditional medicinal purposes. (Weinheimer and Jonna, 2003)

Roughtail stingrays have an excruciating venomous sting, which serves as their primary defense if stepped on or threatened. In some cases, their sting has been fatal to humans. Although rays are more commonly found in water depths of 50 to 200 m, they occasionally travel to shallower waters, posing a threat to humans. (Mitchill, 2008; The IUCN Red List of Threatened Species, 2010)

Although roughtail stingrays are not considered threatened, their large size and low fecundity make them vulnerable to population decreases. They are sometimes taken as bycatch or are accidentally caught through trawl fishing, artisanal fisheries and other fishing practices. (The IUCN Red List of Threatened Species, 2010)