Hellbenders, also called "devil dogs" and "snot otters", are considered to be living fossils because they have changed so little over time. They are large, stout-bodied, fully-aquatic salamanders that grow to be two feet long with brown, grey or black skin with lighter markings. Hellbenders have flattened bodies and heads that allow them to cling to the river bottom, as well as a rough pad on their toes for traction on slick rocks. They have paddle-like tails for swimming, and numerous folds of fleshy skin for oxygen absorption. Their eyes are small, without lids, and their skin secretes toxic slime to ward off predators.
