Rattlesnakes are unique to the Americas. Deserts, and grass, and scrublands to subtropical thorn scrub.
Rattlesnakes can sense warm-blooded prey in the dark.
The deep pit between the rattlesnake's eye and nostril detects the heat of warm blooded prey. The rattlesnake has 2 of these pits and belongs to a group of snakes called pit vipers. Some boas and pythons have slit-like organs in their lips that serve a similar function. The snake's tongue is harmless. The tips of the forked tongue pick up odorous particles from the snake's surroundings and transfer them to Jacobson's organ in the roof of the mouth, which is believed to combine the senses of taste and smell.