Why do you have to preserve animals endargered?

We need to protect endangered species becausell animals are part of a delicate ecosystem. If we disrupt that system, horible things can happen, things that effect humans. For instance, if we kill of the bats, they are not around to control pest. The pests could kill off trees. The trees death could cause other animals to die etc.... etc..... We shouldn't change nature, the earth has been perfecting the balance for millions of years. We also need to protect endangered species because they are amazing creatures and we have no business killing them off.