Spotted river stingray

Potamotrygon motoro

Order: Myliobatiformes

Family: Potamotrygonidae

Genus: Potamotrygon

The Spotted River Stingray is a large, round-bodied freshwater ray with an eye-catching pattern of golden or orange spots—called ocelli—outlined in black against a grey or brown background. These striking spots give rise to its alternate name, the ocellate (or “eyed”) stingray. Its flattened body conceals its mouth and gill slits underneath, while the eyes and spiracles are positioned on top. A long, whip-like tail extends behind the body and contains one or more venomous barbs for defence.

HEAD AND BODY LENGTH

Up to 40–50 centimetres (16–20 inches) disc width, sometimes larger in females

TAIL LENGTH

Tail length can equal or exceed body width; includes a venomous spine

WEIGHT

Varies, but generally up to 15 kilograms (33 pounds) in large individuals

Conservation Status: IUCN

Distribution

Native to the Amazon, Orinoco, and Río de la Plata basins. Its range spans several South American countries where it inhabits large river systems and seasonal floodplains.

Habitat

Prefers slow-moving, sediment-rich freshwater environments, including sandy-bottomed rivers, oxbow lakes, and flooded forests. It often buries itself partially in the substrate to ambush prey or hide from predators.

Diet

Carnivorous. It feeds on small fish, worms, insect larvae, and crustaceans. The ray detects prey using electroreception and crushes it with powerful jaws lined with flat teeth.

Reproduction

Viviparous (live-bearing). After internal fertilization, the embryos initially rely on yolk sacs, then receive uterine "milk" (histotroph) from the mother. Litters typically range from 2 to 8 pups, which are born fully formed and independent.