Western Rattlesnake

An irritated Western rattlesnake beginning to coil and ward off a potential predator.

NPS/

Slithering through grass, shrubs, sand, and rocky hillsides the Western rattlesnake (Crotalus oreganus) can survive in a number of environments. Its long slender body uses sideways friction to navigate the terrain and occasionally climb branches in shrubs and small trees to wait for unsuspecting birds that will serve as a meal.

While the snake is able to see with its narrow vertical pupils, its vision is poor in comparison to other adaptations that allow it to capture its prey. The eyes contain a large number of rod cells used for seeing in the dark. While this greatly improves the snake's night vision, the lack of cone cells used for seeing in the light keeps it from sharply defining images.

Another adaptation the snake uses to locate its prey includes a forked tongue to smell the air. The piston-like movements of the tongue allow chemicals to make contact with a sensory organ much like that of a nose. After quickly processing the chemical information the snake is able to act.

Often mistaken for nostrils, rattlesnakes exhibit visible sensory pits on their triangular head. These pits contain a membrane that can detect a fractional difference in temperature of infrared radiation from their warm prey. Instead of relying on their eyes at night they can use this organ to hunt and capture their prey.