The Cortez round stingray, like other stingrays, has a flattened body, with expanded pectoral fins that are fused to the head and body to form a round, flat disc (3). However, round stingrays differ from other stingray species in having a significantly shorter tail, about equal to or slightly less than the length of the disc, and a well-developed, rounded caudal fin. No dorsal fins are present (2) (4). As the name suggests, the disc of the Cortez round stingray is roughly circular in shape, with a slightly angular snout. The skin is smooth, and the upper surface of the body is brown or brownish grey in colour, with variable, irregular, relatively widely spaced dark blotches and spots (2) (5). A long, venomous spine is located halfway along the upper side of the tail (3) (4) (6).
The taxonomy of this small stingray is currently being investigated, as it may form a single species with the similar bullseye round stingray, Urobatis concentricus, which in turn may be a colour morph of the round stingray, Urobatis halleri (1). However, the Cortez round stingray can be distinguished from U. halleri by the dark blotches on its disc (4).
- Also known as
- Cortez stingray, Spotted round ray, spotted stingray.
- Urolophus maculatus.
- Total length: up to 42 cm (1) (2)
- Disc width: up to 26 cm (1) (2)
Cortez round stingray biology
Very little information is available on the biology and life history of the Cortez round stingray (1). However, like other stingrays, it is likely to be ovoviviparous, the female retaining the eggs inside the body until they hatch, and then giving birth to live young (4) (6). Reproduction in this species may be similar to the closely related U. halleri, in which mating occurs during the winter months, and the female gives birth to three to six young, after a gestation period of around three months (4). As in many ray and skate species, the male Cortez round stingray has more pointed, curved teeth than the female, an adaptation thought to allow the male to grasp the female’s pectoral fins during copulation (7).
Most stingray species spend a lot of time camouflaged on the sea bed, often partially buried in the mud or sand, but can swim rapidly when disturbed or when pursuing prey (3). The diet typically includes bottom-dwelling invertebrates, such as crustaceans, molluscs and worms, as well as small fish. Buried prey may be exposed by scooping out the sand or mud using the snout and pectoral fins (3) (4). The venomous tail spine of this and other stingrays is used in defence, and, although not fatal to humans, it can cause painful wounds (3) (4) (8).
Cortez round stingray range
The Cortez round stingray has a rather limited distribution, being found only in the Mexican Pacific Ocean, in the Gulf of California (1) (2) (5).
Cortez round stingray habitat
This bottom-dwelling stingray usually occurs over rocky bottoms in coastal waters, particularly in sheltered areas near islands and in bays, lagoons and estuaries (1) (2). It may be found at depths of around 2 to 20 metres (2).
Cortez round stingray status
Classified as Data Deficient (DD) on the IUCN Red List (1).
Cortez round stingray threats
Although round stingrays are generally of little commercial value, due to their small size (1) (8), the Cortez round stingray may occur as bycatch in other fisheries. When caught, it is usually returned to the sea, but the tail is often cut off, probably resulting in high mortality (1). The restricted range of this species may make it particularly vulnerable to any threats, but the current lack of information on its biology, abundance and taxonomy, and on levels of bycatch, make it difficult to accurately assess its conservation status (1).
Cortez round stingray conservation
There are currently no specific conservation measures in place for the Cortez round stingray. The IUCN have recommended that management plans be developed and implemented for all shark and ray species in Mexico, although this has yet to be put into action (1). Further research into the biology, populations and conservation status of this small stingray are urgently needed before any appropriate conservation measures, if necessary, can be put into place.
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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 anemones), 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)
- 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.