You're all wrong. Animals belong on my plate, next to the taters and coleslaw. ;-P
Seriously though, not arguing for or against zoos, but I wonder about the bigger picture, and the roles that (good) zoos play? Consider how many school groups tour through the Toronto zoo each year. How many kids are inspired to make choices that positively affect the animal kingdom? To preserve natural habitat etc. ? I wonder how many wide eyed kids look at the zoo animals and set their career goals then and there? I'd be willing to bet that a great number of today's wildlife biologists, conservationists, and so on first got their "spark" by visiting animals in a zoo, conservatory, canned safari, or the like.
I just wonder, thinking big picture here, if each species is better off "as a whole" because a small percentage of them are in captivity for human education, understanding, and yes, entertainment. Just a thought.
As "proof" (extra big quotation marks) of this, I'm sitting here looking at my kid's pile of children's books. Consider how animals were portrayed in early children's stories. The big bad wolf. Bears that are little girls. Lions that terrorized villages and so on. There were fewer educational zoos back then. Then look at today's children's books, and you'd be hard pressed to find one book that paints an animal in a negative light. Now, there's lots of zoos around... Coincidence??? I think not! That's some hard scientific sciencing science fact right there! Class dismissed. ;-p