We interrupt your regularly scheduled news programming to bring you this wonderful piece of trivia about kangaroo genitals.
Regular readers will know of my love for Inside Nature’s Giants, the British documentary where anatomists cut up large animals to examine how their bodies work and evolved. It’s a truly incredible show, combining unbridled joy at the natural world, drama, and solid educational value.
So far, it has brought us the horrifying throat of a leatherback turtle, the mysterious bloodsweat of a hippo, and the exploding insides of a beached whale. But this week’s episode may have topped all of that with the triple vaginas of the female kangaroo. The diagram above (an annotated screengrab from the show) explains the complicated plumbing.
This set-up is shared by all marsupials – the group of mammals that raise their young in pouches. Koalas, wombats and Tasmanian devils all share the three-vagina structure. The side ones carry sperm to the two uteruses (and males marsupials often have two-pronged penises), while the middle vagina sends the joey down to the outside world.
Note that the ureters, which carry urine from the kidneys to the bladder, pass through the gaps between the three tubes. In placental mammals, like us, the ureters develop in a different way, and don’t go through the reproductive system. As we develop, the precursors to the reproductive tubes eventually fuse into a single vagina. In marsupials, this can’t happen.
The programme also suggested that this might explain why marsupial embryos are born at such a premature stage of development. A kangaroo’s joey is about the size of a jellybean when it leaves the vagina, and it must endure an arduous crawl into the pouch. It’s possible that with such a narrow tube to go down, it couldn’t get any bigger before its birth.
With its complicated reproductive set-up, a female kangaroo can be perpetually pregnant. While one joey is developing inside the pouch, another embryo is held in reserve in a uterus, waiting for its sibling to grow up and leave. Indeed, a mother kangaroo can nourish three separate youngsters at a time – an older joey that has left the pouch, a young one developing inside it, and an embryo still waiting to be born.
Go Further
Animals
- Soy, skim … spider. Are any of these technically milk?Soy, skim … spider. Are any of these technically milk?
- This pristine piece of the Amazon shows nature’s resilienceThis pristine piece of the Amazon shows nature’s resilience
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them?
Environment
- This pristine piece of the Amazon shows nature’s resilienceThis pristine piece of the Amazon shows nature’s resilience
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
History & Culture
- Gambling is everywhere now. When is that a problem?Gambling is everywhere now. When is that a problem?
- Beauty is pain—at least it was in 17th-century SpainBeauty is pain—at least it was in 17th-century Spain
- The real spies who inspired ‘The Ministry of Ungentlemanly Warfare’The real spies who inspired ‘The Ministry of Ungentlemanly Warfare’
- Heard of Zoroastrianism? The religion still has fervent followersHeard of Zoroastrianism? The religion still has fervent followers
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
Science
- NASA has a plan to clean up space junk—but is going green enough?NASA has a plan to clean up space junk—but is going green enough?
- Soy, skim … spider. Are any of these technically milk?Soy, skim … spider. Are any of these technically milk?
- Can aspirin help protect against colorectal cancers?Can aspirin help protect against colorectal cancers?
- The unexpected health benefits of Ozempic and MounjaroThe unexpected health benefits of Ozempic and Mounjaro
- Do you have an inner monologue? Here’s what it reveals about you.Do you have an inner monologue? Here’s what it reveals about you.
Travel
- Follow in the footsteps of Robin Hood in Sherwood ForestFollow in the footsteps of Robin Hood in Sherwood Forest
- This chef is taking Indian cuisine in a bold new directionThis chef is taking Indian cuisine in a bold new direction
- On the path of Latin America's greatest wildlife migrationOn the path of Latin America's greatest wildlife migration
- Everything you need to know about Everglades National ParkEverything you need to know about Everglades National Park