The rattle is the rapid sound-making organ in a rattlesnake’s tail.
A rattlesnake’s rattle consists of interlocking, hollow keratin segments. When the snake contracts specialized tail muscles, the segments vibrate against one another and create the familiar buzzing sound. New segments are added when the snake sheds its skin, although old segments can break or wear away.
The rattle is primarily a warning signal. It can alert large animals, including humans, that the snake feels threatened and may strike. It is not a detachable stinger, and the snake does not shake it because the tail contains a separate sound-producing bone.
A common misconception is that counting rattle segments reliably reveals a snake’s age. That is not dependable: segments can be lost, and snakes may shed several times in a year or less often depending on growth, health, and conditions. The rattle’s structure is more useful for identification than for precise aging.