Like other stingrays, the bullseye round stingray has a flattened body, with expanded pectoral fins that are fused with the body and head to form a round, flat disc (3). However, round stingrays differ from other stingrays in having a significantly shorter tail, about equal to the length of the disc, as well as a well-developed, rounded caudal fin. There are no dorsal fins (2) (4). As its common name suggests, the disc of the bullseye round stingray is roughly circular in shape, with a rounded snout, and is generally light grey with blackish blotches and spots arranged in concentric rows. Two yellowish or cream bands surround the disc (2) (5). The skin is smooth, without spines (2) (5), but a long, venomous spine is located approximately halfway down the length of the tail, and is used in defence (3) (4) (6).
The taxonomy of the bullseye round stingray is currently under investigation, with some believing it to be a colour morph of the round stingray, Urobatis halleri, rather than a full species (1) (7).
- Also known as
- Bullseye stingray, concentric stingray, reef stingray, reticulated round ray, spot-on-spot round ray.
- Urolophus concentricus.
- Raie Ronde Concentríque.
- Raya Redonda De Manchas.
- Total length: up to 47.5 cm (1)
- Disc width: up to 28 cm (1) (2)
Bullseye round stingray biology
Almost nothing is known about the biology and life history of this stingray (1). However, like other stingrays, it is likely to be ovoviviparous, meaning the eggs hatch inside the female and the young are born live (4) (6). Reproduction in this species may be similar to the closely related U. halleri, which mates during the winter, and gives birth to three to six young, after a gestation period of around three months (4). As in many rays and skates, the male bullseye round stingray has much more pointed, curved teeth than the female, an adaptation thought to aid the male in grasping the female’s pectoral fins during copulation (8).
Most stingrays spend a lot of time camouflaged on the sea bed, often partially buried, but can swim rapidly when disturbed or when pursuing prey (3). The diet typically includes bottom-dwelling invertebrates, such as crustaceans, molluscs and worms, and small fish. Prey may be exposed by using the pectoral fins and snout to scoop out holes in the sea bed (3) (4). Although not fatal to humans, the venomous tail spine can cause painful wounds if this stingray is stepped on or disturbed (3) (4) (9).
Bullseye round stingray range
The bullseye round stingray has a rather restricted distribution, occurring only in the Gulf of California, Mexico (1) (2) (5) (7).
Bullseye round stingray habitat
The bullseye round stingray typically occurs on rocky bottoms in coastal waters, bays, lagoons and estuaries, and also on sandy bottoms near reefs, at depths of around 5 to 20 metres (1) (2) (7).
Bullseye round stingray status
Classified as Data Deficient (DD) on the IUCN Red List (1).
Bullseye round stingray threats
Round stingrays are generally of little commercial value (9), mainly as a result of their small size (1). However, the bullseye round stingray is occasionally taken as bycatch in other fisheries. When caught, it is not usually retained, but the tail is often cut off before returning the stingray to the sea, probably resulting in high mortality (1). The restricted range of the bullseye round stingray may make it particularly vulnerable to any threats, but the lack of available information on its biology, abundance and taxonomy, and on the levels of bycatch, make assessing its conservation status difficult (1).
There are no conservation measures currently in place for the bullseye round stingray. The IUCN recommend that a management plan is required for the conservation and sustainable management of all shark and ray species in Mexico, and investigations are underway to clarify whether the bullseye round stingray is indeed a full species (1). Further research is urgently needed into the biology, abundance and conservation status of this little-known stingray before it can be better protected.
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- In the fishing industry, the part of the catch made up of non-target species.
- Caudal fin
- The tail fin of a fish.
- Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
- Dorsal fin
- The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
- The state of being pregnant; the period from conception to birth.
- Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anenomes), echinoderms, and others.
- A diverse group of invertebrates, mainly marine, that have one or all of the following; a horny, toothed ribbon in the mouth (the radula), a shell covering the upper surface of the body, and a mantle or mantle cavity with a type of gill. Includes snails, slugs, shellfish, octopuses and squid.
- Pectoral fins
- In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
- The science of classifying organisms, grouping together animals which share common features and are thought to have a common ancestor.
- IUCN Red List (July, 2009)
- Allen, G.R. and Robertson, D.R. (1994) Fishes of the Tropical Eastern Pacific. University of Hawaii Press, Honolulu, Hawaii.
- Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
- Round Stingray Biological Profile, Ichthyology Department, Florida Museum of Natural History (July, 2009)
- Castro-Aguirre, J.L. and Pérez, H.E. (1996) Listados Faunísticos de México. VII. Catálogo Sistemático de las Rayas y Especies Afines de México (Chondrichthyes: Elasmobranchii: Rajiformes: Batoideiomorpha). Instituto de Biología, Universidad Nacional Autónoma de México, Mexico.
- ReefQuest Centre for Shark Research (July, 2009)
- Goodson, G. (1988) Fishes of the Pacific Coast: Alaska to Peru, including the Gulf of California and the Galapagos Islands. Stanford University Press, Palo Alto, California.
- McCourt, R.M. and Kerstitch, A.N. (1980) Mating behavior and sexual dimorphism in dentition in the stingray Urolophus concentricus from the Gulf of California. Copeia, 4: 900 - 901.
- Ebert, D.A. (2003) Sharks, Rays, and Chimaeras of California. University of California Press, Berkeley.