Nature has a juvenile sense of humor. That, at first, seems like the only explanation for why certain turtles, among them the Australian Fitzroy river turtle and the North American eastern painted turtle, breathe through the back end. Both turtles can breathe through their mouths if they so chose.
Although all birds rely on internal fertilization for reproduction, the males of just 3% of bird species actually possess penises —instead, males and females alike invert and bring together their cloacas, a basic opening through which all the birds' various bodily emissions pass.
Why bother digesting, when the Cloaca machine can do it for you?
Cloaca No.5 isn't some fancy perfume from Paris—far from it. It is actually an elaborate reproduction of the human digestive system produced by Belgian artist Wim Delvoye. And all it does is poop.