Unlike mammals that have only one genitalia, koalas, kangaroos, wombats, Tasmanian devils, in fact all marsupials have three genitalias. The reason for this we will try our best to explain.
The entry point of the marsupial connects to three genitalias on the inside of the animal. The two outside genitalia allow for the fertilisation of the egg in the uterus, while the middle genitalia sends the joey down and into the outside world. The gestational period of marsupials is only four to five weeks because marsupials have not developed a complex placenta to protect the baby from the mothers immune system. When a kangaroo is born it is only the size of a jelly-bean.
Surprisingly, because of this amazing system a female kangaroo can remain perpetually pregnant. It is possible for a female to nourish three joeys at the same time. It can have one that has left the pouch, but is too small to fend for itself and still needs to feed from its mother. One developing inside the pouch, and another as an embryo held in reserve in the uterus, waiting for its opportunity to enter the pouch.
