A rattlesnake is a venomous snake that lives in North and South America, famous for the warning sound it makes with its tail. At the end of a rattlesnake's body, hollow segments of old skin stack together loosely. When the snake shakes its tail rapidly, these segments knock against each other and create a buzzing or rattling noise that sounds like dried beans shaking in a can.

This rattle serves as a warning system. When a rattlesnake feels threatened, it coils up and shakes its tail to say “stay back!” The snake would rather save its venom for hunting prey like mice and rabbits than waste it on something too big to eat.

Rattlesnakes come in many species, from the small pygmy rattlesnake to the six-foot-long eastern diamondback. They're pit vipers, which means they have special heat-sensing organs that help them hunt warm-blooded prey in total darkness. Like all snakes, rattlesnakes are cold-blooded and spend sunny days warming themselves on rocks.

Despite their fearsome reputation, rattlesnakes generally avoid humans and strike only when surprised or cornered. They play an important role in controlling rodent populations across deserts, grasslands, and forests throughout the Americas.