Science/Tech

Meet The Animal That's Always Pregnant

If you think being pregnant for nine months is tough, then try getting pregnant all the time. That’s exactly what swamp wallabies are doing and it’s the only marsupial to ever do it.

The Animal That’s Always Pregnant

Naturally, a wide array of animals can become pregnant for a number of times during their adulthood. However, because mammals are known for looking after their young, there is usually a healthy pause after birth since the mother gives their babies some time to get nursed and reared for a brief period of time. There are, of course, other mammals that only give birth to one or two offspring in their entire lifetime.

The swamp wallaby, however, is a much different, even strange, story. Found throughout eastern Australia, these small hopping marsupials have adult females that are, surprisingly enough, almost always pregnant. This is because the animals can conceive one to two days before giving birth, and it’s actually a common behavior for them to do so, per a new paper published Monday in the scientific journal Proceedings of the National Academy of Science.

Because they’re marsupials, swamp wallabies also have pouches in their bodies, where their tiny, immature babies crawl inside to get some milk. But that’s where a lot of the similarities end between other marsupials (besides looking like some sort of pseudo-kangaroo) because while kangaroos can mate and conceive just a day after birth, swamp wallabies can do it before even giving birth. In other words, the animal can get pregnant even while it’s already pregnant.

“There are a whole range of reasons why you don't want to conceive during active pregnancy. Part of that is anatomical. Most animals have one uterus, or womb; if a developing embryo is already there, there’s no room for more. Marsupials, however, have two uteruses, each with their own associated ovary and cervix,” Brandon Menzies, a study co-author and researcher at the University of Melbourne, said.

It’s certainly a unique way of reproducing, with the females getting pregnant again before giving birth, allowing them to wean the firstborn and be ready for another birth once the joey is weaned and out of the pouch, after which the mother wallaby has ovulated and mated again.

brush-tailed-rock-wallaby-4367746_1920 Swamp wallabies are the only marsupials that can get continuously pregnant. Photo by Pixabay (CCO)

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