A.O.T.D. (Animal of the Day) Rattlesnake

The Rattlesnake! A very dangerous venomous species that rattles its tail when threatened. "The rattle is composed of a series of nested, hollow beads which are actually modified scales from the tail tip". The rattle noise is made when these beads shake up against each other. New ones are formed each time a snake sheds its skin. Baby rattlers cannot make the noise since they only have one bead at the time of birth. It isn't until their first molting that they gain the additional bead and have something to rattle against.