When a rattlesnake is born he has a small rounded tip on his tail known as the pre button. Several days after his birth he will shed his skin for the first time and lose this pre button which the button will replace. This is the first segment of his rattle. But it takes at least two rattle segments to produce any noise. He will gain this ability with his next skin shedding. Thereafter throughout his life he will add a rattle segment with each shedding. It is unusual to find more than eight or nine segments on a wild caught rattlesnake because of the wear and breakage of the terminal segment(s).
On rare occasions rattlesnakes are found without a rattle. This condition will be permanent if the rattle matrix that forms the rattle segments has been lost or severely damaged.
Each rattle segment is a separate piece unto itself and is not permanently attached. Each segment is continually being pushed away from the tail by the addition of new rattle segments formed by the matrix.
The protuberances of a single segment interlock loosely with the segments directly above and below it. When the rattlesnake vibrates his muscular tail, it causes each separate segment to bounce against the adjoining ones creating the buzzing sound.
*The Mexican Island, Santa Catalina, in the Gulf of California is the home of the Santa Catalina Island Rattlesnake (Crotalus Catalinesis). Known as the rattleless rattlesnake. It is in every other respect a true rattlesnake, but the tails of these rattlesnakes terminate in an abrupt non-tapering fashion and do not rattle.