humans have a wide variety of body parts similar to all the animals, yet all things things are all contained inside one mass. both the zoo an a body have a system in order to function. there are many zoos that all interact with eachother, sometimes even trading animals which is like humans social lives, or maybe even surgeries. and the zoo has to close everyday so it can be cleaned and readied for tomorow the way people have to sleep in order to energize. just a couple of ideas... : } alsoo, We have a variety of bacteria and viruses and sometimes parasites living inside us. We're like a self-contained miniature safari.