The Western Diamondback Rattlesnake is a venomous pit viper (or pitviper). The "pits" referred to are actually heat receptors that aid the snake when striking at warm blooded prey. These pits are found midway between the eyes and nostrils and are clearly visible in the photo. Send us an email if you can't find them! When threatened a rattlesnake will generally coil up and shake it's rattle as a warning. The rattle is formed when the snake molts as it is a remnant of the molted skin.