Dasyatis americana

Geographic Range

Southern stingrays are found in the the western Atlantic Ocean from New England to Brazil, with abundant populations in the Caribbean Sea, Gulf of Mexico, Grand Cayman Island, British West Indies, Bahamas, coastal Belize, and the southern coast of Florida.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native
• atlantic ocean atlantic ocean
  • native native

Habitat

Southern stingrays are a marine species and are generally found in shallow waters (about 2 meters deep) of bays filled with sea grass beds and algal fields.

• Habitat Regions
• temperate temperate
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• benthic benthic
• reef reef
• coastal coastal

Physical Description

This species is an elasmobranch (a cartilaginous fish) in the superorder Batoidea . Batoid species have a broad, flat, disc-shaped body that is formed by the fusion of the dorsoventrally flattened body, pectoral fins, and the head. In southern stingrays, the body and pectoral fins are expanded to form a diamond-shaped disc, which is about 1.2 times as broad as it is long, with females generally being larger than males. The disc width of Southern stingrays raised in captivity ranges from 48 to 53cm in males and 75 to 80cm for females. In captivity, the maximum reported disc width for male is 80cm and for female is 150cm. Wild southern stingrays have reached a maximum disc width of 200cm and a weight of 97kg. The tail can be up to twice as long as the body, and carries a sharp, serrated, venomous spine that is used in defense. The gills are located on the underside of the body. The eyes are located on top of the head, which is elevated above the rest of the body. Due to its feeding habits and elevated head, southern stingrays have spiracles that enable them to take in water dorsally. The skin is covered with denticles, which are scale-like body coverings. Body coloration ranges between dark gray, green, and brown.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry
• venomous venomous

• Sexual Dimorphism
• female larger

Development

Fully-developed young are born soon after hatching from their egg capsules, which occurs inside the mother's body. Hatchlings resemble minature versions of their parents.

• Development - Life Cycle
• indeterminate growth indeterminate growth

Reproduction

Very little is known about the mating systems of southern stingrays. However, one study was able to report observations based on a single female southern stingray mating with two males. The female was followed by the two males, with one male eventually biting and holding onto her pectoral fin. This male then positioned himself so that his pelvic region was curled toward the female’s urogenital opening (also known as the cloaca). The male then flipped upside down and thrust his pelvic region in a rapid sequence for 10 to 33 seconds. Following this, the male released his bite from the female’s pectoral disc. Females are able to mate again soon after giving birth

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Age at sexual maturity varies with the geographical region. In captivity, females were impregnated, and thus considered mature, at about 5 to 6 years. Males, on the other hand, were considered mature at about 3 to 4 years. Maternal size is positively correlated with the number of offspring, which can range from 2 to 10. Stingrays that are raised in captivity bear young biannually, while in wild stingrays, it is usually once a year. Breeding behavior has been observed in early September in the Grand Cayman Islands, and in late August at Bimini, Bahamas. Gestation period ranges from 125 to 226 days with a mean of 175 days.

Southern stingrays use both primary and secondary nurseries for the development of young. The primary nursery is a habitat where a female gives birth to her offspring, while the secondary nursery is habitat where juveniles reach maturity. Little is known about the specific locations of these nurseries and migration of the offspring between the two habitats. In Belize, Glovers Reef is a known primary nursery where adult southern stingrays only visit seasonally for mating or to give birth. Scientists caught juvenile southern stingrays during the months of May, November, and December at a depth of 10 to 20 m on nearby rocky reef surfaces, which is believed to be a secondary nursery.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• induced ovulation induced ovulation
• fertilization fertilization
  • internal internal
• ovoviviparous ovoviviparous

Southern stingrays are ovoviviparous (producing young by means of eggs that are hatched inside the body of the female), meaning that unborn young are protected by the mother due to developing inside her body. During early development, the embryo uses a yolk sac for its nutrition. After the yolk sac is absorbed, nutrients are provided by the mother through the secretion of histotroph ("uterine milk"). No further parental investment occurs after the young stingrays are born.

• Parental Investment
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Very little is known about the average lifespan of this species. In a single study, the oldest age recorded for males was 12 years. The oldest recorded female was estimated to be 13 years old.

Behavior

Southern stingrays are generally solitary, but will form groups for mating purposes, when resting, or for predator protection. They are generally nocturnal, benthic predators that excavate their prey by flapping the pectoral fins and jetting water from the mouth to disturb the substrate and uncover their (usually) buried prey. Southern stingrays propel themselves through the water using undulatory locomotion, which is provided by their pectoral fins. This movement method provides a high level of maneuverability, which is required for foraging and escaping predators. One study suggests that Dasyatis species may move with the tide, with high tides providing increased food supply.

• Key Behaviors
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• solitary solitary

Home Range

Southern stingrays are known to move over large distances and may forage in a very broad area from day to day. However, quantitative estimates for individual home ranges (assuming they exist), are currently unavailable.

Communication and Perception

One report speculates that southern stingrays may communicate using pheromones. It was observed that the birth of offspring attracts males, leading scientists to suspect that birth produces some kind of olfactory attractant that alerts neighboring males, perhaps arising from organic molecules produced in the female's cloaca. Since female southern stingrays are able to mate soon after parturition, these could be considered to be sexual pheromones. Males occasionally touch females before, and bite them during mating, which may also serve in some communicative capacity.

Like other elasmobranchs, southern stingrays are equipped with highly developed senses of smell. They also possess thousands of Ampullae of Lorenzini on their undersides, particularly concentrated around the head, which allow them to sense electrical field produced by buried prey. Elasmobranchs also have lateral lines for sensing vibrations in the water, and a well-develped sense of hearing. The eyes of southern stingrays are not likely to be useful in sensing prey, being placed on top of the head. However, they are still rather large and well-developed and are likely used to sense predators and other disturbances in the water above.

• Communication Channels
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical
• electric electric

Food Habits

Southern stingrays feed on multiple organisms throughout the day (more so at night), so they are considered to be continuous foragers and opportunistic feeders. One study found the stomach contents of a southern stingray to include prey from 15 families, in four phyla. Major prey were crustaceans, small fishes, and worms.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

• Animal Foods
• fish
• mollusks
• aquatic or marine worms
• aquatic crustaceans

Predation

The main predators of stingrays are humans. Another predator of southern stingrays are great hammerhead sharks ( Sphyrna mokarra ). The shape of this shark’s head enables it to hold down stingrays while feeding on them. Stingrays will often bury themselves in the sand to avoid detection by predators, and will also use their venomous tail spine in self defense.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Southern stingrays act as predators of several marine fish and invertebrate species, as well as serving as prey to larger cartilaginous fish species (particularly hammerhead sharks). A commensal foraging relationship has been documented between southern stingrays and double-crested cormorants ( Phalacrocorax auritus ), which are common coastal birds ranging from North Carolina to the Gulf of Mexico. As stingrays excavate the substrate in search of prey, they often stir up fish. The birds dive in and swim behind the stingrays to feed on snappers and grunts, though this is only possible in shallow waters. This stingray foraging habit also attracts follower organisms, which remain near a host in hopes of finding food. Some observed follower organisms of stingrays include Caranx bartholomaei , Caranx latus , Cephalopholis fulva , Halichoeres radiatus , Halichoeres dimidiatus , Dactylopterus volitans , and Lactophrys trigonus . Bluehead wrasse ( Thalassoma bifasciatum ) serve as mutualistic cleaner organisms for southern stingrays.

Economic Importance for Humans: Positive

In developing countries, southern stingrays are an important food resource. Southern stingrays are also a large tourist attraction in coastal and island locations throughout their range. A popular tourist site for stingray interaction, “Stingray City Sandbar”, is located in the Cayman Islands. About 150 southern stingrays are found there yearly. The stingrays at this location are found during the day and in a very crowded space, where tourists can hand feed them. The venoms found in association with the spines of stingrays are currently being researched for possible applications in biomedical and neurobiological applications.

• Positive Impacts
• food food
• ecotourism ecotourism
• source of medicine or drug source of medicine or drug
• research and education

Economic Importance for Humans: Negative

Southern stingrays are not known to be aggressive towards humans. Since the they are often found buried in the sand in shallow waters, it is easy to step on them. When stepped on, they will use their venomous spine in self-defense.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous

Conservation Status

Because southern stingrays are large elasmobranchs with relatively low reproductive rates and slow growth, they are at risk of overfishing. Currently, this species has no special conservation status. Populations near the United States appear to be healthy, but there is little information on the populations in other areas where fishing pressure is heavier.

Growing tourism also appears to be affecting southern stingray populations. This is illustrated by the case of “Stingray City Bar”. This species is normally active at night and is a solitary forager, but at this site it is found during the day (when tourist activity is high) and in close proximity with conspecifics year-round. The continuous supply of food keeps the stingrays in this area and causes alterations to their behavior. Another issue is the hand feeding of these wild animals with foods such as squid, which are not found in their natural diet. Long term feeding with these abnormal foods can negatively impact southern stingrays by affecting their health and mobility.

Additional Links

Encyclopedia of Life

Contributors

Ivana Pavic (author), Radford University, Joel Hagen (editor), Radford University, Jeremy Wright (editor), University of Michigan-Ann Arbor.

References

Brooks, D., M. Mayes. 1980. Cestodes in four species of euryhaline stingrays from Colombia. Proceedings of the Helminthological Society of Washington , 47: 22-29.

Cartamil, D., J. Vaudo, C. Lowe, B. Wetherbee, K. Holland. 2003. Diel movement patterns of the Hawaiian stingray, Dasyatis lata : implications for ecological interactions between sympatric elasmobranch species. Marine Biology , 142: 841–847.

Chapman, D., M. Corcoran, G. Harvey, S. Malan, M. Shivji. 2003. Mating behavior of southern stingrays, Dasyatis americana (Dasyatidae). Environmental Biology of Fishes , 68: 241–245.

Gardiner, J., R. Hueter, K. Maruska, J. Sisneros, B. Casper, D. Mann, L. Dernski. 2012. Sensory Physiology and Behavior of Elasmobranchs. Pp. 349-401 in Biology of Sharks and Their Relatives, Second Edition . Boca Raton, FL: CRC Press.

Gilliam, D., K. Sullivan. 1993. Diet and feeding habits of the Southern stingray. Bulletin of Marine Science , 52(3): 1007-1013.

Henningsen, A., R. Leaf. 2010. Observations on the Captive Biology of the Southern Stingray. Transactions of the American Fisheries Society , 139: 783–791.

Henningsen, A. 2000. Notes on Reproduction in the Southern Stingray, Dasyatis americana (Chondrichthyes: Dasyatidae), in a Captive Environment. Copeia , 2000(3): 826-828.

Kajiura, S., L. Macesic, T. Meredith, K. Cocks, L. Dirk. 2009. Commensal Foraging Between Double-crested Cormorants and a Southern Stingray. The Wilson Journal of Ornithology , 121(3): 646–648.

Kohn, A., S. Cohen, G. Salgado-Maldonado. 2006. Checklist of Monogenea parasites of freshwater and marine fishes, amphibians and reptiles from Mexico, Central America and Caribbean. Zootaxa , 1289: 1-114.

Passarelli, N., A. Piercy. 2006. "Southern Stingray" (On-line). Florida Museum of Natural History. Accessed April 29, 2012 at http://www.flmnh.ufl.edu/fish/Gallery/Descript/SouthernStingray/SouthernStingray.html .

Pikitch, E., D. Chapman, E. Babcock, M. Shivji. 2005. Habitat use and demographic population structure of elasmobranchs at a Caribbean atoll (Glover’s Reef, Belize). Marine Ecology Progress Series , 302: 187-197.

Rosenberger, L. 2001. Pectoral fin locomotion in batoid fishes: undulation versus oscillation. The Journal of Experimental Biology , 204: 379-394.

Saunders, D. 1958. The occurrence of Haemogregarina bigemina Laveran and Mesnil, and H. dasyatis n. sp. in marine fish from Bimini, Bahamas, B.W.I.. Transactions of the American Microscopal Society , 77: 404-412.

Sazima, C., J. Krajewski, R. Bonaldo, I. Sazima. 2007. Nuclear-follower foraging associations of reef fishes and other animals at an oceanic archipelago. Environmental Biology of Fishes , 80: 351-361.

Semeniuk, C., W. Haider, A. Cooper, K. Rothley. 2010. A linked model of animal ecology and human behavior for the management of wildlife tourism. Ecological Modelling , 221: 2699–2713.

Semeniuk, C., K. Rothley. 2008. Costs of group-living for a normally solitary forager: effects of provisioning tourism on southern stingrays Dasyatis americana . Marine Ecology Progress Series , 357: 271–282.

Semeniuk, C., B. Speers-Roesch, K. Rothley. 2007. Using Fatty-Acid Profile Analysis as an Ecologic Indicator in the Management of Tourist Impacts on Marine Wildlife: A Case of Stingray-Feeding in the Caribbean. Environmental Management , 40: 665–677.

Snelson, F., S. Gruber, F. Murru, T. Schmid. 1990. Southern Stingray, Dasyatis americana : Host for a Symbiotic Cleaner Wrasse. Copeia , 1990 (4): 961-965.

Strong, W., F. Snelson, S. Gruber. 1990. Shorter contributions: ichthyology. Copeia , 1990(3): 836-840.

Yokota, L., R. Lessa. 2006. A nursery area for sharks and rays in Northeastern Brazil. Environmental Biology of Fishes , 75: 349-360.