North American Snakes: The Good, the Bad and the Beautiful

Set aside your fears, and you conception of them as symbols of evil. Most North American Snakes aren't the least bit dangerous to humans.

North American snakes - western rattlesnake
Venomous pit vipers such as the western rattlesnakes (and also cottonmouths and copperheads) have vertical pupils. Pit vipers also have heat-sensing pits between their eyes and nostrils.
Dwight Kuhn