Rattlesnake
Crotalus cerastes
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Serpentes
Family:	Viperidae
Subfamily:	Crotalinae
Genera
Crotalus Linnaeus, 1758 Sistrurus Garman, 1883

The rattlesnake is a kind of snake, a reptile. About 50 species of rattlesnakes are known: they are a kind of pit viper.

There are two groups of rattlesnakes: the genera Crotalus and Sistrurus. All have a venomous bite, and some are much more dangerous than others. Pit vipers have a set of heat-sensing "pits" on their heads which help them find prey and move towards it, even in the dark.

The name rattlesnake is used because they have a special tail with several parts on the end that can make a loud bzzzz sound, or rattle. This defends them against predators and large animals. It acts as a warning signal.