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. (Chapman, et al., 2003; Gilliam and Sullivan, 1993; Henningsen and Leaf, 2010; Kajiura, et al., 2009)
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. (Cartamil, et al., 2003; Semeniuk and Rothley, 2008; Yokota and Lessa, 2006)
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. (Henningsen, 2000; Passarelli and Piercy, 2006; Rosenberger, 2001)
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. (Passarelli and Piercy, 2006; Pikitch, et al., 2005; Yokota and Lessa, 2006)
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 (Chapman, et al., 2003)
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. (Chapman, et al., 2003; Henningsen and Leaf, 2010; Henningsen, 2000)
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. (Henningsen and Leaf, 2010; Henningsen, 2000)
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. (Passarelli and Piercy, 2006)
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. (Henningsen and Leaf, 2010)
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. (Cartamil, et al., 2003; Rosenberger, 2001; Semeniuk and Rothley, 2008; Semeniuk, et al., 2010; Semeniuk, et al., 2007)
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. (Cartamil, et al., 2003)
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. (Chapman, et al., 2003)
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. (Gardiner, et al., 2012)
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. (Gilliam and Sullivan, 1993)
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. (Cartamil, et al., 2003; Passarelli and Piercy, 2006; Pikitch, et al., 2005)
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 Carangoides 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. (Brooks and Mayes, 1980; Kajiura, et al., 2009; Kohn, et al., 2006; Saunders, 1958; Sazima, et al., 2007; Snelson, et al., 1990)
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. (Semeniuk, et al., 2010; Semeniuk, et al., 2007)
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. (Passarelli and Piercy, 2006)
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. (Semeniuk and Rothley, 2008; Semeniuk, et al., 2010; Semeniuk, et al., 2007)
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. (Semeniuk and Rothley, 2008; Semeniuk, et al., 2010; Semeniuk, et al., 2007)
Ivana Pavic (author), Radford University, Joel Hagen (editor), Radford University, Jeremy Wright (editor), University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
parental care is carried out by females
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
Animals with indeterminate growth continue to grow throughout their lives.
ovulation is stimulated by the act of copulation (does not occur spontaneously)
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying.
chemicals released into air or water that are detected by and responded to by other animals of the same species
an animal that mainly eats fish
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
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