Ok, dolphins, I get. Dolphns are the only other animal known to man that is so self aware it thinks about suicide.
The reason that they kick you out of dolphin shows so fast is not to clean the staging area for the next show. It's because the dolphins have atendencyto beach themselves in anattemptto kill themselves out of misery (watch "the cove"). I won't support those shows for that reason, but as for other zoo animals... It depends. I believe wholeheartedlyin saving endangered species. There's really not a whole lot we can do to restore the habitats to what they used to be. (coming from the guy who wants to preserve swamps). We can preserve what's there now, and in small chunks fix the problem, but if the human population is going to keep rising (and it's believed that it will hit 10 billion before we see our limit, there's only so much we can do.
And if we are saving them, why not let people be able to visit and see a polar bear that they'd never see other wise? Plus, it's a great way for zoologists to study animals instead of having to go out into the wild and spend days, weeks, or months hoping to find what they are looking for. If we didn't have bats in zoos, we might not understand WNS as well as we do now