Spouting Alligator

Some alligators can submerge themselves slightly underwater and vibrate their bodies so that numerous

individual water droplets are projected upward simultaneously a foot or more directly above the backs of their heads. What is the physics here?

Answer

To eject water droplets upward, the alligator head vibrations must provide the initial energy to create nearly standing waves in the shallow water on the back of its head. As wave crests become larger, droplets of water break off and are projected high above the surface. One can simulate this effect by sliding a styrofoam cup filled with water across a finished wooden surface at about 10 centimeters per second. Water droplets will shoot upward to about 20 centimeters.