Hellbenders—also known as snot otters and devil dogs—have dwindled throughout their range, which once encompassed streams from northeastern Arkansas to New York.

The 2.5-foot-long (0.7-meter-long) amphibians have declined by 80 to 90 percent in most of their traditional watersheds in recent decades, and healthy populations now haunt only isolated pockets of southern Appalachia (see map) and Pennsylvania, said Dale McGinnity, curator of reptiles at Nashville Zoo.

All of the states in the hellbender's range have protected the species, and the U.S. Fish and Wildlife Service is currently reviewing whether to give the hellbender federal protection, McGinnity said.

The reasons for their decline is unknown, but