Originally posted by DriftingGuy:
They look poisonous
That's because they are
(AKA freshwater stingray), Paratrygon, Plesiotrygon, Potamotrygon.Length: Most river rays are about 12 to 18 inches across (30 to 45 centimeters), but Paratrygon can be up to 60 inches across (152 centimeters).
Color: Wide variety of camouflage patterns.
Range: Freshwater river systems of northern South America.
Remarks: There are about 20 species of South American freshwater river rays, or stingrays, with more than 50 varieties of color patterns. Most are found in the Amazon River basin and belong to the 3 genera. Feared more by locals than piranha, people can become sick for days from the river ray's sting. The enzyme on the poisonous barb can cause muscle tissue to dissolve, which is very painful. If the wound is not treated properly, death is a possibilty. River rays are the only chondrichthyans to live their entire lives in freshwater. They have evolved from stingrays that once inhabited the oceans but were eventually cut off from saltwater a long time ago.
Status: Common throughout northern South America, some of the more exotically colored species are popular in the aquarium trade and wild populations should be monitored.
http://www.anchoragemuseum.org/arch_Ray_Troll/changing_exb1_8.asp