[Audio of rattlesnake ... rattle. Colston: Whenever I shake them really fast, they bump together, producing a sound. Narrator: Because the rattle is hollow inside, sound waves can bounce off ...

Rattlesnakes shed multiple times a year and could have any number of segments at any particular time. In addition, the rattle is made of hollow keratin, which is fragile and often breaks off.

They often try to warn you off by shaking their rattle, but that's not something you can count on. Here is what you need to ...