Amazon River: X-rays expose new species of Stingrays

Biologists recently fished out two new species of freshwater stingray from a river in the Amazon rainforest near Iquitos, Peru.

The animals have been put into a new genus - the first time this has been done for stingrays since 1987.

At first glance the creatures look like nothing so much as freckled pancakes with feeble tails. But X-rays revealed an elaborate skeleton in which hundreds of slivers of cartilage fan out radially to support the fish's floppy disc-shaped body.

Biologist Nathan Lovejoy of the University of Toronto, Canada, and his colleagues dubbed the new stingrays Heliotrygon gomesi and Heliotrygon rosai. The creatures, which can grow up to half a metre long, have beady eyes, suggesting that they inhabit the murky depths.

Unusually, the stingrays lack barbed tails - they are stingless - possibly because they do not have to contend with any serious predators. Like other freshwater stingrays, the new species likely hide on the bottom of the river, waiting to pounce on any prey that swims to close and swallow their meal with vacuum-like jaws.