The raised spiracles, or breathing holes, that allow giant freshwater stingrays to breathe while hiding under riverbed mud are clearly visible on a newborn on March 31, 2008, in Thailand.

The baby was born in the busy Bang Pakong River, where populations of the massive fish appear surprisingly healthy. Yet the rays are still listed as "vulnerable" on the World Conservation Union's 2007 Red List of Threatened Species.

"We know almost nothing about its abundance and habitat needs," biologist Zeb Hogan said.

"That makes it extremely difficult to manage the species."

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