This Week in Zoology: Kangaroos


I harbored a passion for Zoology from a very early age, so my American grandmother used to tape science T.V. shows for kids and mail them to me when I was little. During an episode of (I think) Kratts’ Creatures, I heard a great story about how kangaroos got their name.

The story is that, when Captain Cook arrived in Australia, he was shocked by the odd creatures he found there. Spotting a kangaroo, he asked an Aborigine who happened to be there “Excuse me, what do you call that strange animal over there?”. The Aborigine replied “Kangaroo”, which meant “I don’t understand you”, and lo the kangaroo got its funny name.

A quick search through the internet of the etymology of the word kangaroo leads me to believe that this story is a myth. However that hardly matters, because there are plenty of strange and interesting facts about kangaroos which are perfectly true, no myths necessary.

  1. Kangaroos don’t really sweat. Rather, they have specialized salivary glands, which secrete a saliva which is different from the one they secrete when they eat, and they lick their forearms to cool down.
  2. The female kangaroo has three vaginas. Two are connected to two separate uteri, while the third is used as a birth canal. This allows the kangaroo to be pregnant far more often than most mammals.

This is useful because the kangaroo, as I am sure you know, is a marsupial. This means that their young are born at a far earlier stage of development than those of true mammals. These fetuses exit the birth canal and find their way to the pouch, where they nurse and continue to develop and grow. Even when they are sufficiently developed to be able to leave the pouch, they still return to nurse for some time.

However, as I am sure you can imagine, the nutritional requirements of a developing fetus is quite different from those of a fully formed joey. So, as the kangaroo’s multiple vagina model permits her to have two joeys at different stages of development, how does she combat this problem?

The female kangaroo is capable of producing two different kinds of milk, one in each of her teats, depending on what stage of development the joey suckling on that particular teat is at.

I find that to be mental.

I have no idea what molecular cues drive that ability, but it puts the kangaroo, in my opinion, in the top ten of nature’s Top Chefs.

By the way, given the popularity of my occasional “This Week in Zoology” segments in the office, my colleagues have taken to throwing out names of random animals to see if I have any odd facts about them stored in the recesses of my brain. If any of you want to do the same, include them in the comments!

Comments

  1. Lofty says

    Regardless of the name that capt Cook chose for the ‘roo, there were hundreds of mutually unintelligible native languages across the continent. So of course 99% of the natives you met in your travels would have NFI what the word “kangaroo” meant.

    Sadly even though they have truly remarkable reproductive strategies to get them through the boom/bust cycle of the eccentric southern climate, they don’t have any traffic sense and many thousands die every year in vehicle collisions. They live in the paddocks around our road and you really need to travel at 40km/h to have a chance of not clobbering them. Not many people travel that slowly. Western style agriculture with permanent water means they’re quite plentiful around populated areas even during the worst droughts.

  2. sonofrojblake says

    Terry Pratchett had a good take on this. Can’t remember which of his early books it was featured a mountain called Mount Your Finger You Fool.

    • AeolianPlankton says

      The Forest of Skund, in the Light Fantastic! There was also a mountain whose name translated to “Who is this fool who does not know what a mountain is?”, or something like that. I think he riffed on that theme again in The Last Continent, but the quote escapes me

  3. Holms says

    Odd kangaroo fact: in times of nutritional crisis (during a drought usually), the female kangaroo will shutdown nutritional supply to the gestating joey, killing it to spare the mother.

    • thoughtsofcrys says

      Interrupting gestation is something that many animals can do, I might have to write another week in zoology about animal abortions 🙂

  4. lorn says

    There is a similar story, possibly apocryphal, about the Yucatan peninsula involving a western explorer pointing to the land and asking what it was called. The story relating that the term Yucatan was the word for ‘I don’t know’. Over the years I’ve heard the same story in various forms from three or four different people.

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