Tuesday, June 5, 2012

Marsupials Have Three Vaginas

Marsupials are mammals that give birth to relatively undeveloped young, and then raise them in pouches. Examples of marsupials that we all know are kangaroos, wombats, koalas, and Tasmanian devils. 

Apart from the pouch, they all have another thing in common: female marsupials possess three vaginas. 

Image: Inside Nature's Giants
The side ones carry sperm to the two uteruses while the middle vagina sends the baby down to the outside world. And since there are two vaginas for transporting sperm, male marsupials often have two-pronged penis.

This kind of reproductive system actually enables female marsupials, say kangaroos, to be pregnant all the time.  In fact, female kangaroos can raise three babies at a time--one that has left the pouch, another recently crawled into the pouch, and another developing as embryo.
A joey latching on to a nipple. Image: gold-coast-aus.com
And this might also explain why marsupials give birth to undeveloped young. A newborn joey must make its own into the pouch all on its own upon birth, so it can only grow to the size of a jelly bean before the vagina becomes too small to crawl through.

*Imagine getting stuck in a kangaroo's vagina*

info: http://blogs.discovermagazine.com/notrocketscience/2012/04/17/kangaroos-have-three-vaginas/

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