Short-tailed river stingray
Potamotrygon brachyura (synonym: Trygon brachyurus ) is the largest representative of people living in South America freshwater stingrays.
Dissemination
The species occurs in large, slow- flowing rivers in northeast Argentina, Uruguay, Paraguay and Brazil. It is primarily in the river system of the Rio de la Plata, distributed in the middle reaches of the Río Paraná, Rio Paraguay and Rio Cuiabá. The densest component is found in the middle reaches of the Uruguay River and the Rio Paraná. P. brachyura adheres preferably in lagoons, backwaters and above sandbanks.
Description
Potamotrygon brachyura has small eyes and a nearly circular shape. The reinforced with a venomous stinger tail is short and muscular. The disc body becomes a maximum diameter of 95 centimeters. The maximum weight of the skate is 200 kilograms. The back is light to dark brown ground covered on most of a black polygonal mesh pattern.
Way of life
Is relatively little known about the widespread nature. Their way of life is adapted to the water level of the great rivers: The Paraná River, the skate show at low water during the months of August and September and with increasing flood during the months of March and April, migratory behavior. In the period between October and November they can be easily identified and harpooned by fishermen in the riparian vegetation. The reproduction rate of the animals is low. Potamotrygon brachyura is ovoviviparous. A female can take up to 19 fully developed young fish to the world. The slow growing juveniles initially feed on small invertebrates, later of molluscs, crustaceans and small fish. Adult animals often lie motionless and well camouflaged in shallow shorelines on the sand floor and lie in wait for prey.
Economic Importance
Despite its tasty flesh he is little trapped. As best time to catch the months of December to April are. Although the export of freshwater stingrays from Brazil is illegal, young animals are occasionally available in the aquarium trade. These are mostly wild caught. In captivity, the offspring is considered to be difficult.
Relationship with people
At the Río Paraná Potamotrygon brachyura is feared locally from fishermen and bathers. It can be difficult to make out in the murky water through its body coloration adapted to the environment. If it feels threatened, he fights back. With strokes of his cock he can cause severe injury. Become arteries taken, they can also be deadly. In addition, his mucus contains toxins and can be introduced into the wound, leading to bacterial infections, and at worst to gangrene.
Threat status
The habitat of Potamotrygon brachyura is increasingly threatened by pollution and dam construction for hydroelectric plants. Thermal baths in Uruguay are often cleaned with hot water and this is then discharged into rivers, which can lead the way to heat shock.