Generally I would agree with statements above. It greatly shows for me what a zoo practically is. I would like to add something small but for me really important note - a zoo, especially a zoo of XXI century, should be a place which creates significance-meaning, constructs and images of animal species and other zoology-related themes (e.g. ideas connected with zoology, conservation).
I think that being a "park with a lot of animals" and even speaking "we save species" is way too small today (however very important, at least that second one).
I mean a situation: almost everyone knows what a lion is - or tiger - and has in their had a meaning of lion/tiger. What about showing and creating meaning of little charming tree-climbing master (like margay)? Doing something like Madagascar done with lemurs - now people know and love lemurs.
So for me a zoo is a place which combine a conservation breeding with building meanings of [less-known] species. Because I see it in the middle - on the one side is science and on the other a park for pleasantly spending time with nature. For me this situation has a lot of possibilities to save nature.
Maybe, I feel it more idealistically and yes, I know I'm not master of English... (however I tried!)