Madagascar Golden Orb Weaver

Other common names: Whip stingray

This species has a sharp-tipped, diamond-shaped disc which is roughly 1.2 times as wide as it is long, giving the species a rather square, angular appearance. The disc extends in front of the head at the front of the body. The head is elevated, preventing it from making contact with the seabed while the ray is resting. The dorsal fin is either absent or indistinct. The frontal portion of the tail is rounded in cross-section; the rest is flattened and serrated, with 52-80 teeth along its length. A venomous spine is present at the base of the tail; its length is approximately equal to the distance between the eye orbits. The tail itself can be twice as long as the disc. The animal is typically dark grey above, but colouration is variable through grey, green and brown with adults often being more olive or brown than juveniles. The lower surface is white.

Similar species: Other rays typically have a less angular disc; that of the Caribbean stingray (Himantura schmarde) is oval. The Atlantic stingray (Dasyatis sabina) has a tail that is oval in cross-section. Additionally, the Atlantic stingray has a more triangular snout, a more rounded disc, and is considerably smaller.

HABITAT

The southern stingray is a bottom-dwelling species in coastal and estuarine waters. It is principally a shallow-water species with a preference for open, sandy habitats, though has been on reefs and among seagrass beds. The species has been recorded from waters whose temperatures are between 28-32ºC.

Depth: 0-53 m, generally below 26 m

BEHAVIOUR

This species forages continually, using electroreception and smell to detect prey. Rays use the motion of their wings to clear sand from the bottom, exposing prey items. Animals are typically solitary, but have been recorded in pairs or larger aggregations on occasion. When heavily-parasitised, individuals may visit cleaning stations attended by cleaner wrasse.

Diet: Fish, large invertebrates, bivalves and marine worms.

Courtship behaviour: Courtship appears to take place in the form of a pre-mating pursuit, following which copulation occurs.

BIOLOGY

Breeding biology: In captivity the species breeds biannually, though little is known about reproductive activity in the wild. Like many rays, Dasyatis americana gives birth to live young, nourishing developing embryos internally on a yolk sac and, once this is exhausted, on uterine secretions. Gestation takes up to 11 months, with litters consisting of an average of 4 young, and a maximum of 10. Litter size appears to be correlated with the size of the adult female. Females may engage in multiple matings before giving birth, and may mate again soon afterwards.

Life cycle: Animals mature at between quarter and half of their maximum adult size; age at maturity is uncertain. Females mature at a larger size than males.

REFERENCES

Atlantic Stingray (Dasyatis sabina), Field Guide to the Indian River Lagoon, Smithsonian Marine Station at Fort Pierce

Dasyatis americana (Southern Stingray), ZipcodeZoo.com

Fishbase
Florida Museum of Natural History
Marine Bio.org

Southern Stingray, Elasmodivers.com

Southern Stingray (Dasyatis americana) ARKive

Chapman, D.D., Corcoran, M. J., Harvey, G. M., Malan, S. & Shivji, M. S. (2003) Mating behaviour of southern stingrays, Dasyatis americana (Dasyatididae) Environmental Biology of Fishes 63: 241-245
Grubbs, D.R., Snelson, F., Piercy, A., Rosa, R.S. & Furtado, M. (2006). Dasyatis americana. In: IUCN 2008. 2008 IUCN Red List of Threatened Species