A passel of possums

December 1, 2013 • 5:37 am

Good morning! The possum family (15 plus mother) is on its way to church.

Fun possum facts!

  • The species name is Didephis virginiana, and it’s the only marsupial in North American north of Mexico. (Do you know which marsupials inhabit Mexico? Answer here.)

The Virginia opossum is noted for reacting to threats by feigning death. This is the genesis of the term “playing possum”, which means pretending to be dead or injured with intent to deceive. In the case of the opossum, the reaction seems to be involuntary, and to be triggered by extreme fear. It should not be taken as an indication of docility, for under serious threat, an opossum will respond ferociously, hissing, screeching, and showing its teeth. But with enough stimulation, the opossum will enter a near coma, which can last up to four hours. It lies on its side, mouth and eyes open, tongue hanging out, emitting a green fluid from its anus whose putrid odor repels predators. Besides discouraging animals that eat live prey, playing possum also convinces some large animals that the opossum is no threat to their young.

  • As you see above, they are prolific breeders. As NatureWorks notes:

An Virginia opossum female may have as many as 25 babies, but she usually will have between seven to eight. The reason opossums have so many babies to insure that some of them survive. Like most marsupials, opossums are very small when they are born – about the size of a navy bean.

The babies climb up the mother’s fur and into her pouch where they find a teat. Some babies will not find their way to the pouch and will die. If they make it to the pouch, only babies who find one of the thirteen teats will survive. They will stay in the pouch and suckle for 55-60 days. Then they will move out of the pouch and spend another four to six weeks on their mother’s back. In some parts of their range, females will have three litters a year.

That’s a theoretical maximum of 75 babies born per year, but the real maximum surviving is 39.

  • They have short life spans: only 1.5-2 years in the wild, up to four in captivity. That’s unusually short for a cat-sized mammal.  One theory suggests that this is due to the high mortality rate of adults; there is high predation (“Virginia opossums may be predated upon by a variety of species including owls, domestic dogs, coyotes, red foxes, raccoons, bobcats and large snakes, among others”) and many die in the winter. Evolutionarily speaking, if you suffer high mortality when you’re reproductive, a good strategy is to pump out as many babies as possible. Even if that saps your strength and itself reduces your longevity, you were going to die of something else anyway.  If possums suffered less predation, they’d probably live longer. Indeed, as Wikipedia reports “. . one population on Sapelo Island, five miles off the coast of Georgia, which has been isolated for up to thousands of years without natural predators, was found by Dr. Steven Austad to have evolved life spans up to 50% longer than those of mainland populations.” Now we don’t know if this is an evolved genetic difference, but if they were tested in captivity along with mainland possums, it would suggest that.  One would also predict that the Sapelo Island possums would have fewer offspring than their mainland conspecifics.

Here’s a possum playing dead (but they are not, as the photographer says, “hideous”):

40 thoughts on “A passel of possums

  1. Looks to me like a resurrected 1970s, ecowarrior member of the Wombles of Wimbledon ~ perhaps a zombie going to church then?

    [Memories of crap British children’s TV, “matey” Top Of The Pops DJs, horrible polyester clothes, Brut, sideburns, medallions, hairspray, perms for men & other crimes against good taste. *shudder*]

  2. Death-feigning is puzzling as a defensive tactic, because most predators are also opportunistic scavengers: dead meat is just meat. It can’t possibly work the way it is usually described.
    So it must depend on mimicry not just of a ‘dead’ animal, but specifically of one contaminated with a dangerous level of toxins or pathogens; for such mimicry to be positively selected, diseased or poisoned targets have to occur at relatively high frequency in the same environment, so that predators and scavengers are already under selection to avoid them.
    What poison or pathogen is being mimicked? It may be possible to find out. Maybe it’s been done already. (It’s important to ask how widespread the death-feigning behaviour is, to figure out where and when it’s likely to have evolved)

    1. Possibly they urinate and defecate as well, making them all smelly and gross. There are other animals that play dead as well. My favs are some cerambycid (longhorn) beetles. These too exude a strong smell while they ‘play possum’.

    2. I’m not sure how playing dead works to discourage predators, but I would like to point out that opossums recover from terrible injuries sometimes. If a dog picks up this opossum and shakes it, it won’t die.

      I’ve got an opossum skull, for example, that shows healing of a complete break through the lower jaw near the place where both halves come together. (The animal later died by being hit by a car. Opossums are durable, not smart.)

      1. Ducks that play dead when approached by a fox are more likely to be picked up and then cached than killed. the fox seems to think they are already dead. the duck then ‘wakes up’ later and wanders off. Now, either it is very early and I haven’t had coffee or this is true and I have read the paper somewhere – or both – but I can’t face a google scholar search right now.

  3. The video of the possum walking with its babies is cute. I like possums. It’s funny when people first encounter them. I remember a friend in high school telling me that they didn’t know what this animal was and she and her dad poked it with a stick and the possum grabbed the stick and pulled it and hissed. 🙂 Another time, I explained to my visiting Australian professor, after he described an animal he saw that matched the profile of a possum, that what he saw was indeed a possum and that possums here weren’t like their fluffy possums there.

    My dad recently saved a possum from being killed by some thug who kept kicking it just because he had decided it was ugly. My dad could have been beaten up by this deranged person but he called a wild life group and waited until they arrived, while guarding the possum. It was a pregnant female who played dead when she was attacked by this insane person.

      1. We used to have at least a pair of them come to our house to steal cat kibble left for the feral cats. Very beautiful and fascinating to watch, and they always froze when I opened the front door – kinda like when we used to play ‘Red Light’ as kids. 😀 We haven’t seen them since they developed most of the moraine here.

        1. They gets squished by cars a lot because of that behaviour (freezing). I once stopped my car on a country road (it was safe as no one was behind me) because a possum decided to growl at my car. Look possum, just move. It finally decided to waddle off. I think they are just trying everything in their repertoire when the big beast of a car comes upon them, poor things.

          1. Oh dear, poor things!

            There was recently a raccoon who kept wandering into the middle of the road and just sat there. This happened two days in a row. Needless to say, I were scared for its life. I called the humane society, and the man with the van came for it, but he said that it looked like it was blind. 🙁 It’s eyes looked whitish like that left eye of that lion you pointed out in the photo.

  4. For those interested by the biology of Opossums, I commend a very interesting book by C.G. Hartman on the subject: Possums (1952, Austin : University of Texas press).

    The historical chapters on the discovery of marsupials are particularly fascinating. I was surprised to lrean that early in the XXth century some people were still thinking that the newborns appeared in the pouch, somehow like blossoming on the nipple.

    Hartman is one of the researchers who helped to demonstrate that the newborn marsupial crawls by itself from the urogenital oppening to a nipple. A long journey for the very immature “joey”.

    Desnes Diev

    1. “The species name is Didephis virginiana”

      The genus should be spelled “Didelphys” because it alludes to the fact that females have “two uterus” (bifurcated uterus). But the usage is to write “Didelphis” which means “two dolphins” 🙂

      Desnes Diev

      1. I think that’s a function of the way Linnaeus chose to Latinize the Greek word. He also assumed delphys was a feminine noun – it’s masculine, in fact – thus virginiana should be virginianus. But rules are rules, and the scientific naming rules say that you have to use the first published name, even if it’s spelled wrong!

        1. See what happens when you don’t learn your Greek well? 🙂 You also end up saying things like Philadelphia means the “city of brotherly love”. 🙂

  5. It should not be taken as an indication of docility, for under serious threat, an opossum will respond ferociously, hissing, screeching, and showing its teeth.

    Damned straight. I remember seeing an opossum cornered by a neighbor’s dog. Truly a menacing sight.

  6. Can I post the possum video on my Facebook page? It is very very interestting. Will there be any copyright issues?

  7. Growing up, I have had a few close encounters with possums. Had he walked closer, the stare given to the man making the video would likely have been backed up with lots of loud screeching and a hugely gaped mouth full of very sharp teeth. It is amazing how wide they can open their jaws, and their canines are unusually long. They suddenly do not look cute at all.
    I do not know if they will bite, but I would never want to test it.

  8. I know I’m going to regret this but, shouldn’t they be called “Opossum” in the US and “possum” in Australia? Two different species and all.

    1. Many different species: 100 species of ‘opossums’ in 3 families in South America, one of which (the Monito del monte, Dromiciops gliroides) is more closely related to the Australian marsupial radiation which includes 6 families of ‘possums’ as well as various other non-possumy things. Neither ‘possum’ nor ‘opossum’ denotes a natural monophyletic group, so there’s not much point quibbling about their precise limits.

  9. I like the possums who come around on my place now and then, and I don’t think they are ugly. They like to clean up whatever has fallen on the ground under the bird feeders. Occasionally, one will discover the cat door into the outbuilding where my outdoor cats eat & sleep. I’ll catch a possum eating up the kitty noms now and then. At first I tried to chase them out of the building (doesn’t work) and then resorted to donning my leather gloves and picking it up by the tail and removing it to the outdoors again without harming it (at least I hope it doesn’t harm them). They run off to the woods like nothing ever happened & happily full of kitty noms!

  10. Possums aren’t native to Minnesota but we are seeing more and more here. Even with our milder winters, possums have been seen with frost-bitten ears and tails. They get into the cat noms on my back porch and wash themselves afterward, just like a cat does. They eat rattlesnakes too and are resistant to the venom. Also, there’s a parasite in their feces that is very dangerous for horses. It’s like the equine version of mad cow disease. All in all, very interesting critters.

    1. How are they ‘not native’? Range boundaries of species can shift naturally as fast as the animals themselves can move, and the combination of global warming and outdoor provision of cat noms is a recipe for northward expansion.

  11. If 13 is the maximum number of young that can be fed in the pouch stage, how did 15 happen? Two adoptees? A mother with unusual anatomy? Inquiring minds want to know!

  12. Here is my only original joke: Why did the chicken cross the road? To show the possum it could be done.

    This joke later appeared in the Reader’s Digest, sent in by someone else. I wonder if this is an example of cultural diffusion or independent origin. I have later seen the same joke with turkeys and armadillos.

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