I remember the polar bear they kept in the zoo in Central Park, New York, for many years. Poor thing was called Gus and known as the "bipolar bear" -- the enclosure was small, and there was a pool where he swam in circles obsessively, nonstop, for years. I felt so sorry for that bear. An unbelievably huge creature, just eye-popping -- and he was on the small side as polar bears go. Didn't react to anybody or anything, just going in circles in the water like a machine. One of the walls was transparent, some kind of tempered glass, and he pushed his paws against it when making a U-turn so you could see the underside of the paws -- black, and enormous.
For some reason the sight of an incarcerated wild animal is something I can't handle. I will never visit a zoo again, but there's a few creatures I've seen in the past that I sincerely hope will, in a karmic reincarnation, swap places with those who incarcerated them. And then those who mindlessly enjoy the sight will be turned into whatever these animals eat.