Thursday, July 09, 2015

Possum, Oh Possum!

The possum has been back. And this time, I've got a better picture.

Sort of a big rat with bad hair. And long toes.

I've been confused about the name; is it possum, or opossum?  And is that the same as the Mexican tlacuache?

I Googled it, and now the confusion has doubled.

The American possums are actually called opossums, scientific name, Didelphimorphia. But for some reason, they are more commonly referred to as possums. ... Australian possums are (scientific name) Phalangeridae. Both are marsupials, but that’s about it. Other than that, they are not really related at all.(From BobInOz)

Here's Wikipedia on the American possums:

The opossums, also known by their scientific name Didelphimorphia ..., make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. Of South American ancestry, they entered North America following the connection of the two continents.
...
The word "opossum" is borrowed from the Virginia Algonquian (Powhatan) language ... from the Proto-Algonquian word meaning "white dog" or "white beast/animal".
They are also commonly called possums, particularly in the Southern United States and Midwest. However, the term "possum" was borrowed into use to describe distantly related Australian marsupials (specifically those of the suborder Phalangeriformes) when Australia became known to Europeans.

They originated in South America, from where one species spread into the American Southeast, and then west and north to here. And in each country in Latin America, they go by a different name: "tlacuache" (from an Azetc word) in Mexico, which is the name I knew, and ...

en El Salvador como tacuazines ... en Ecuador como guanchacas, en Honduras como guasalos, en el PerĂº como mucas o canchalucos, en Bolivia como carachupas, en Colombia como faras, chuchas, runchos o raposas, en Venezuela como rabipelados ... (From Wikipedia in Spanish)

And the Latin name, Didelphimorphia, means "double womb", referring to the split reproductive system; baby possums are born very early in their development, and crawl up the mother's belly to a pouch where they attach themselves to a teat and grow until they're ready to face the world. They are marsupials, like the better-known kangaroo.

Looking up names, I learned that some of the things I "knew" about possums were wrong.

  • "Possum" has been used in the phrase, "playing possum," referring to the habit of a threatened oppossum of keeling over and pretending to be dead. Except that they don't, really, all that often; only about 10% of possums play dead.

  • They are also supposed to have prehensile tails, but this only shows up in the young; an adult is too heavy for his own tail.

UPDATE: Christopher Taylor adds, in the comments,

The "double womb" is actually a bit more literal than that. Unlike the situation in humans, where the Fallopian tubes lead from the ovaries on each side to a common central uterus, marsupials have an entirely separate uterus for each ovary, with a separate vagina for each (though only a single cervix, so I think there would still be only a single visible opening externally). I believe many male marsupials have a divided head to the penis, so that they are able to fertilise both sides of the female's reproductive system at once. Even though this feature is (I think) common to all marsupials, I suspect that Didelphis was the animal that got tagged with it because, of course, the American opossum was discovered by Europeans long before the Australian forms.

Two uteri, and a pouch, to boot! And then the mother carries her babies on her back for weeks after they're out of the pouch. The burden of motherhood is a heavy one for an opossum!

10 comments:

  1. And the Latin name, Didelphimorphia, means "double womb", referring to the split reproductive system

    The "double womb" is actually a bit more literal than that. Unlike the situation in humans, where the Fallopian tubes lead from the ovaries on each side to a common central uterus, marsupials have an entirely separate uterus for each ovary, with a separate vagina for each (though only a single cervix, so I think there would still be only a single visible opening externally). I believe many male marsupials have a divided head to the penis, so that they are able to fertilise both sides of the female's reproductive system at once. Even though this feature is (I think) common to all marsupials, I suspect that Didelphis was the animal that got tagged with it because, of course, the American opossum was discovered by Europeans long before the Australian forms.

    (And now let's see if the software thinks this is spam.)

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  2. Thanks, Christopher! That is fascinating! I had seen something about that divided penis, but with no other information about it, so I was left wondering if I'd misunderstood even that.

    I am going to update the post with your comment, because not everyone goes on to read comments.

    And no, it didn't register as spam. :)

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  3. I had no idea how complex these creatures are, and with a zillion different names. Thank you for the research and the info. Wonderful!

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  4. I live in South Florida and have seen Opossums in my yard late at night. One day in the morning, a mother opposum was coming from the next yard into mine under the fence that separates the two properties. I could see her coming from an "eyehole" in the wood fence. She had at least 6 babies on her back. Since Opossums have lousy eyesight, she pushed under the fence and walked within 1 foot of me as I stood stock still. The really cute part is that 2 of the babies fell off her back when she scooched under the fence. As she continued, they made the funniest little sneezing noises to call her back. Back she went, picked them up and put them up on her back with the others, and then on she went. I loved witnessing that - the babies were pretty big and were having a very bumpy ride as they tried to hold on.

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  5. Susan, that is so cool! A good memory!

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  6. ceratina3:53 pm

    There's a good free book (pdf) about opossums, complete with photos:

    http://web.missouri.edu/~krausew/Histology/Home_files/opossum.pdf

    They are very strange beasties indeed! Not just the strange-to-us reproductive system. They seem to be immune to most venoms and toxins due to a single protein in their blood (lethal toxin-neutralizing factor (LTNF)), which is now being researched as a universal antivenin.

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  7. Thanks for the link, ceratina! That's a very informative book: everything from electron microscope photos of sperm to how to care for rescues, with full descriptions and clear writing. Excellent!

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  8. When we lived in Los Angeles our house was in the dry hills near a large regional park. We often has possum visitors. Before we got rid of our kitty door, they would come inside and help themselves to cat food in the kitchen. Guess you know why we got rid of the kitty door (not to mention the racoon and skunk that also came to visit). We would chase the possums around the house and corner them in a cat carrier. That's not fun with all the hissing and bared teeth. Then we would drive our visitor back to the park for relocation. Not much fun in the middle of the night when you have to get up early to get to work using those horrible freeways. It's so much better now that we live up north. - Margy

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  9. Margy, and they have so many teeth, too; sharp, pointy ones! I wouldn't want to have to deal with a wild possum in my house in the middle of the night.

    The last time I had a kitty door, I would find a neighbour's cat fast asleep on my bed.

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  10. Check out my post on possums and THE CUTEST PICTURE EVER!!!! xoxo!

    http://countrycitycindy.blogspot.com/2015/07/cute-overload-information-about.html

    Cindy

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If your comment is on a post older than a week, it will be held for moderation. Sorry about that, but spammers seem to love old posts!

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