Foot-flagging frog

Foot-flagging frogs live under thundering waterfalls of the island of Borneo in southeast Asia. Calling is not much of a help in such a noisy environment, so these frogs use additional visual signals to communicate - they raise their hind leg and wave. Also, they flicker their vocal sacs. The lighter colouration on the foot skin and throats makes their signals more visible. Evolution always finds a way.