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An Opossum’s Opposable Thumbs

11-22-16-opossum-hind-foot3-untitled-1Virginia opossums have expanded their range into northern New England, but are still not commonly seen, except, perhaps, lying on roads where they met their demise. There is much to admire about opossums: they are the only North American marsupial, they have more teeth than any other North American land mammal (50) and they possess a prehensile tail and opposable thumbs (both of which are rarities among non-primates).

The recent discovery of a road-killed opossum provided me with an opportunity to examine its feet at close range. An opossum’s front feet have five toes, each bearing a nail. Their hind feet also have five toes, but only four of them have nails. The fifth toe, or “thumb,” lacks a nail and is opposable, allowing opossums to grasp branches and to climb. If you see their tracks, the hind foot is easily discernable from the front due to the fact that the thumb is at a 90-degree angle to the other toes.

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13 responses

  1. Marilyn

    It’s awesome to be able to examine a creature minutely, and marvel at its adaptations and beauty.

    November 22, 2016 at 7:25 am

  2. Alice Pratt

    So both photos are the left rear foot?

    November 22, 2016 at 7:33 am

  3. kpmaxon

    I grew up in the south, part of the time in southern Virginia. A late-night teenage driving game is the Possum Stop. Similar to the old Chinese Fire Drill — when a possum is spotted in the middle of the road, the driver slams the brakes and everyone leaps out to chase the hapless creature. Beer often involved ;-0

    November 22, 2016 at 7:42 am

    • That is great – I’ve never heard of this practice, but bet it saved lots of possums from getting run over!

      November 22, 2016 at 8:05 am

  4. Such strange-looking hands… Thanks for the interesting post!

    November 22, 2016 at 8:19 am

  5. Kathie Fiveash

    It is fascinating that the opossum only has the opposable thumb on the hind feet. I would imagine that this limits its use to grasping and climbing. Most animals with opposable thumbs have them on their front “hand” and use them at least partly for manipulating tools. Since the hand, eye, and brain are so connected, it makes me wonder about the evolution of intelligence, and tool use, and how closely they are connected to opposable thumbs on the front feet/hands.

    November 22, 2016 at 8:57 am

  6. Kathryn

    I have seen a few here and there and it always surprises me. I guess as the earth warms up we’ll be seeing more species that we are not accustomed to.

    November 22, 2016 at 10:33 am

  7. and, wow, look at the padding. What purpose does that serve?

    November 23, 2016 at 9:41 am

    • I wondered that myself…possibly enhances gripping?

      November 23, 2016 at 10:53 am

  8. Gloria Moses

    About a couple of months ago, my son showed me one out in our yard. (We do have ducks and geese). Then a friend who lives just over a mile from my house posted a picture of one that was in her trash can. I heard about another one in a chicken coop just down the road. This is in Island Pond, Vermont, which is 17 miles from the Canadian border.

    November 25, 2016 at 12:48 am

    • Wow! You are almost at the northern tip of their range!

      November 25, 2016 at 8:58 am

    • Gloria Moses

      Yes, that is why I was so surprised that this one wasn’t just a fluke.

      November 25, 2016 at 9:12 am

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