Rumble In The Jungle

They look cuddly, but don't be fooled: red-eyed treefrogs (Agalychnis callidryas) have a secret dark side. When Michael Caldwell, of the Smithsonian Tropical Research Institute, filmed the frogs under infrared light he saw a behavior had hadn't seen before -- the frogs started vigorously shaking the branches they were sitting on. Caldwell and colleagues, decode the meaning of the shakes.