I don't claim to be an expert on all things animal but I have spent the last ten years working with or for animals or conservation efforts. What I have learned, I learned from my own experience, books, papers, articles, photographs, documentaries and from others who have taken the time to share their knowledge with me.
One of the rebuttals to my objection to zoos often comes from the parents of young children (and the zoos themselves, on behalf of their visitors with young children), who claim that children couldn't possibly learn about animals if they didn't go to the zoo. My response is normally to point out what a child cannot learn from looking at animals in the zoo.
No matter how hard we stare at a tiger, we will not learn about his natural habitat, the vital role that he plays in his native ecosystem and the dire need for in situ conservation efforts if he and other members of his species are to survive beyond the next few decades. We could look all day at a polar bear and learn nothing of global warming and melting ice caps. We can admire orang-utans and come away non-the-wiser about palm oil plantations. We can marvel at chimpanzees and learn nothing of human-wildlife conflict and the bush meat trade. Of course, zoos can provide signs, guidebooks and talks to describe these things but what we can actually learn from looking at the animals themselves, beyond their size and shape, is debatable. And yet, animals are held captive for their entire lifetimes in zoos; purportedly so we can learn from them.