cloaca

In zoological anatomy, a cloaca is the posterior opening that serves as the only opening for the intestinal, reproductive, and urinary tracts of certain animal species. All amphibians, birds, reptiles, and monotremes possess this orifice, from which they excrete both urine and feces, unlike most placental mammals, which possess two or three separate orifices for evacuation. The cloacal region is also often associated with a secretory organ, the cloacal gland, which has been implicated in the scent-marking behavior of some reptiles, amphibians, and monotremes.