In animal anatomy, a
cloaca (plural
cloacae ) 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".