Having just come from the “Jews owning dogs” thread, I think that there are people here that should ask a shailah if one is allowed to go to a zoo. Zoos are full of tumahdik animals. Of course, the bittul Torah involved in visiting a zoo completely stops a ben torah from even considering a visit to the zoo. Finally, from reading numerous other threads, one must make the obligatory claim that zoos are ossur as makomos pritzus.
As an aside, the zoo in Yerushalayim is excellent.