You are probably wondering why, well its because they are poisouns. Well of course they are, they wouldn't be called the poison dart frog for nothing. They are so poisonous that less than a drop could kill a human. Hunters would catch them and use them for killing other animals. Of course if they were to touch them, then they could die, so they caught them with a leave. They put the poison on a tip of an arrow to kill their food. Or going to be food.
The poison dart frog is very, VERY small! It is about one cm big! (That's probably why it is so hard to catch!) It is smaller than a penny!
