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sighthoundman t1_j9nftdf wrote

Oh, boy do they have a separate vaginal opening.

There is variation, but the basic plan is that the male has a bifurcated penis. The female has two lateral vaginas, each leading to it's own uterus. In addition, there's a median vagina that opens into near the pouch (marsupium, which gives them their name) and that the babies must crawl from that opening to the pouch immediately* after birth, when they are just feet and lips*.

I rate the Wikipedia article on marsupials essentially accurate. Not worth the time and effort to clean up.

* Eh, close enough.

Edit: eliminated some false facts.

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Peter_deT t1_j9nyzle wrote

The central vagina (used for birth) does not open into the pouch, Typically the mother licks a path from the vagina to the pouch and the new-born crawls along it, into the pouch and latches on to a teat.

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Justadumbuser t1_j9nxflg wrote

So they have 3? Evolution is definitely inventive.

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djublonskopf t1_j9orcrt wrote

Placental mammals (like us) basically start with 3 precursor tubes that fuse together early in development.

In marsupials, the ureters (which transport urine from kidneys to the bladder) pass in between the 3 vaginas, so it would be pretty much impossible for them to fuse without cutting off the transport of urine to the bladder. In placental mammals, the ureters develop differently and no longer pass between the tubes, which is why it's possible for us to fuse the 3 precursor tubes into one.

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NedRyerson_Insurance t1_j9of2je wrote

Is there any difference between marsupials whose pouch opens upward or downward? Are they anatomically the same aside from that switch?

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