Rattlesnakes are one of the most feared group of venemous snakes in the world, but it's not the rattlesnake's fault they meet (and bite) so many people and pets when encountered in the wild.
In fact, they're born with a built-in defense mechanism and warning device that should make people and pets steer clear- the rattle in their tail.
It's terrifying to hear that rattle while you're out enjoying nature, and many animals are innately terrified of the sound, but how do their tails make such a creepy sound?
Daniel and Lincoln from the What's Inside? channel dissected a rattlesnake's tail to see how it rattles, and even though Lincoln was totally grossed out he learned one thing- there ain't no balls in there!