We may not need them---but neither will we need lions and wolfs, but they are mentioned as being in the new earth. God created animals before us, for our enjoyment, to take care of them. We simply love furry creatures--even those without fur. But I doubt we will have alligators and other such as they are for the purpose of thinning out the weakest and sickly and keeping the dead cleaned up from the land--like vultures won't be needed either. But there will be all sorts of animals there and all of them vegetarians, as God originally intended.