Rattlesnakes are venomous pit vipers indigenous to North, South, and Central America. All rattlesnakes possess large, triangular heads, jointed rattles on the end of their tails, and pits on their faces that can sense the heat of prey. When threatened, rattlesnakes shake their tails, producing a rattling sound to warn intruders. There are many varieties of rattlesnake, including timber rattlers, diamondbacks, sidewinders, and pygmy rattlers.
The timber rattlesnake, or crotalus horridis, displays a variety of coloration that includes black, brown, yellow, and gray. All timber rattlesnakes are characterized by dark bands on their backs that are often shaped like chevrons. This banding may be subtle on black specimens. Mature timber rattlers attain a length of 50 to 60 inches (127 to 152 centimeters). Also known as canebrakes, these rattlesnakes have a wide range in the United States (U.S.), inhabiting the midwestern, central, and eastern states.
There are several varieties of diamondback rattlesnakes, which are named for the diamond-shaped pattern on their backs. Western diamondbacks, or crotalus atrox, are found in Mexico and the southwestern U.S. These snakes are commonly called Texas diamondbacks. Adults have thick bodies and can reach a length of 60 inches (152 centimeters). The western diamondback is responsible for the highest number of venomous snake bites in the country.
Crotalus adamanteus, or the eastern diamondback rattlesnake, inhabits the southeastern United States. It is the largest species of rattlesnake known, and has a broad body that can weigh as much as 10 pounds (4.54 kg) at maturity. The largest specimen ever found was 96 inches (244 centimeters) long, but the average adult is usually 33 to 72 inches (84 to 183 centimeters) in length.
Sidewinders, or crotalus cerastes, are characterized by their unusual method of locomotion. Unlike other rattlesnakes, the sidewinder possesses elevated scales above the eyes that resemble horns. This has earned it the nickname horned rattler. It is small compared to some other rattlesnakes, and the adults reach a length of 15 to 30 inches (38 to 76 centimeters). Sidewinders inhabit the southwestern U.S. and are pale in color, displaying light shades of yellow, tan, cream, and pink.
The sistrurus miliarius, or pygmy rattlesnake, is even smaller, and adults reach a length of 14 to 22 inches (38 to 56 centimeters). Although the pygmy rattler reacts like any other rattlesnake by shaking its tail to buzz a warning when threatened, its rattles are so small that they usually cannot be heard. Pygmy rattlers are found in Georgia and the Carolinas. They can exhibit patterns in gray, red, orange, lavender, and tan.