<P> In animal anatomy, a cloaca / kloʊˈeɪkə / kloh - AY - kə (plural cloacae / kloʊˈeɪsi / kloh - AY - see or / kloʊˈeɪki / kloh - AY - kee) is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of certain animals, opening at the vent . All amphibians, birds, reptiles, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles) have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation . Excretory systems with analogous purpose in certain invertebrates are also sometimes referred to as cloacae . </P> <P> 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 . </P>

What body system is the cloaca part of