Rattlesnakes have a rattle of rings on their tail. If they feel threatened, they move it quickly back and forth, 50-60 times per second. The hollow rings rattle against each other and make a fearsome noise. The snake wants to express: "Warning, I'm dangerous, stay away from me." Their venom is so strong that even a gram of it would kill thousands of mice. Therefore, it is also one of the most poisonous snakes in the world. The largest of its kind is the diamond rattlesnake with up to 2.4 m length and 4.5 kg in weight.