TAXONOMY
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes (cartilaginous fishes)
Subclass: Elasmobranchii (sharks, rays and skates)
Order: Myliobatiformes
Family: Potamotrygonidae (river stingrays)
Genus/species: Potamotrygon motoro
GENERAL CHARACTERISTICS: Oval disc, with a greyish-brown upper surface patterned with distinct yellow-orange spots, and a white underside. Like most rays, flat teeth are used to grip and crush prey that is sucked into the ventral mouth. Note periscoping eyes which protrude from sand when buried. Olfaction is a major and well-developed means of perception for these stingrays; their olfactory organs are situated in laterally placed cartilaginous capsules on the top of the head. The spine on the tip of the tail is capable of delivering a painful sting.
Length up to 1 m (3 ft.) and weight to 15 kg (33 lb.).
DISTRIBUTION: South America: Uruguay, Paraná- Paraguay, Orinoco, and Amazon Basins.
HABITAT: Found in freshwater calm waters, especially on the sandy margins of lagoons, brooks and streams. Able to tolerate only a narrow range of salinities. Lost ability to retain urea decreasing osmolarity for fresh water unlike salt water relatives.
DIET: Mostly benthic hard-shelled invertebrates, such as clams, mussels, and crustaceans. Also worms, insect larvae, and small fishes.
REPRODUCTION: Fertilization is internal with the male attaches himself to a female by firmly clamping his jaws onto the posterior margin of her disk, sometimes leaving prominent bite marks. Females produce eggs that hatch inside the female and are then ‘born’ live after a gestation period of no more than three months. The litter size varies, from 3 to 21 young.
LIFESPAN: Maximum of 15 years in captivity.
CONSERVATION: IUCN Red list Data Deficient (DD)
REMARKS: One of the seven species of this genus inhabiting southern South America.
Fishermen also harpoon these rays during floods when they are found resting over vegetation in shallow water. P.motoro apparently has delicious meat.
References
fishbase fishbase.org/summary/Potamotrygon-motoro.html
ARKive www.arkive.org/ocellate-river-stingray/potamotrygon-motoro/
Encyclopedia of Life eol.org/pages/205366/details
IUCN Red List www.iucnredlist.org/details/39404/0
Ron’s flickr https://www.flickr.com/photos/cas_docents/3407966512/in/album-72157608387905158/
Ron’s WordPress shortlink http://wp.me/p1DZ4b-1tm
