An iconic reptile, the rattle of the western diamondback rattlesnake (Crotalus atrox) is one of the most evocative sounds of the arid southern United States. A large and heavy-bodied species, the western diamond-backed rattlesnake’s coloration varies from chalky grey to dull red, appearing dusty due to minute flecks and dots on the scales. As suggested by its common name, this species has diamond-shaped markings over most of its body, which are edged with black and white. These markings are replaced by conspicuous black and white bands towards the rear of the tail, just in front of the rattle, while the head has two characteristic pale stripes, one in front of the eye and the other behind, which run diagonally down the head towards the mouth. Undoubtedly, the most distinctive feature of this species is the rattle. This unusual appendage is composed of loosely connected, interlocking segments made of dead, horny keratin, which knock together when the tail is vibrated, producing the rattling sound. Newborn rattlesnakes are born without a rattle, but acquire segments after each molt, eventually developing as many as ten.
