If you live in North America, you've probably seen a Virginia opossum (Didelphis virginiana). Maybe dead on the road or alive on your porch eating cat food in the middle of the night, but in either case, you might have thought, "Gross, it's a possum!"
But you would have been way off base on several counts.
First of all, a "possum" lives in Australia and is also a marsupial (which means it raises its young in a pouch like a kangaroo), but a completely different species than the one currently snuggling with a half-eaten bag of Doritos at the bottom of your curbside trash can in North Carolina, which is definitely and correctly an "opossum."
"Folks get very confused about this," says Richard Ostfeld, senior scientist at the Cary Institute of Ecosystem Studies in Millbrook, New York. "I've had people tell me triumphantly that they discovered building plans for possum nest boxes and that they planned to install dozens of them to encourage opossums to multiply on their property. But, when I looked up the plans, they were designed for brush-tailed possums in Australia – completely useless for opossums in North America."
Secondly, sure, opossums aren't winning any beauty contests, but they're not gross – even if they wouldn't mind taking that moldy pad thai from the back of your refrigerator off your hands. Some people might be put off by the hairless, prehensile tail, the crocodile mouth full of fearsome, haphazardly-arranged teeth, the beady eyes that seem to lack whites, yet still manage an unhinged, googly look. But opossums are the fastidiously-groomed, most likely disease-free wildlife heroes of your neighborhood. Also, they're, quite simply, fascinating.
Opossums Kill Ticks and Fight Disease
It's a common misconception (possibly prompted by their bumbling swagger) that opossums carry rabies or distemper. In fact, they rarely get these diseases because their body temperature is too low to make them susceptible. Not only do opossums not carry the diseases you think they do, the presence of an opossum in your yard is your best bet for combating Lyme disease.
According to a 2009 study exploring whether blacklegged ticks (the disease vector for Lyme disease) might be regulated by wildlife they parasitize. Of 15 forest dwelling mammals and ground nesting birds, opossums were the only ones to destroy the vast majority (over 95 percent) of all the blacklegged ticks that tried to feed on them.
"Our calculations indicated that a single opossum is capable of killing several thousand larval ticks per week during the late-summer peak," says Ostfeld, who co-authored the study. "We also know that, of those ticks that do successfully feed on an opossum, only a small fraction will become infected with the Lyme disease bacterium. So, opossums are protective in two ways – killing ticks and preventing infection."
A study by the same research team published July 2018 in the journal Ecology found that tick-borne disease risk was reduced in areas where opossums were present.
Opossums Are Smarter Than You Think
For an animal that does more than its fair share of hobbling into traffic and is known for flopping over like a corpse at the merest whiff of danger, opossums are surprisingly intelligent. To begin with, weak eyesight and a nocturnal nature both contribute to the fact that you're probably more familiar with the sight of a dead opossum than a live one. In addition, their primary defense mechanism, playing dead, is almost entirely involuntary – a reaction to extreme stress that leaves the opossum in a death-like coma for a few minutes to a couple hours. And a comatose opossum can take a beating that would kill other animals their size. This, then, might be a great strategy if your mortal enemy is a bear, but not if it's a Toyota.
So, now that we established that their roadkill status has little to do with their intelligence, what makes opossums smart? Turns out they have great memories. Because they spend so much time eating odious leftovers and the like, a 1984 study found that once an opossum tastes a chemical that doesn't agree with it, it will remember and avoid the smell of it for a year afterward.
Opossums are largely nocturnal animals, so if your dog has gone into the backyard at night and begins wildly barking, she probably has an opossum cornered. The standoff could last all night – the last thing an opossum wants is to tangle with your four-legged friend, so he will invariably lay down and play dead until the threat gets bored and passes. Opossums are non-aggressive, docile creatures – they will hiss and show their teeth and try to look very scary when frightened, but are far more afraid than they are to be feared.
Opossums Are Fastidiously Clean
Like cats, opossums are constantly grooming themselves with their paws and tongue, partly in order to make sure they're parasite-free, but also to keep themselves cool (they lack sweat glands, so grooming is like opossum air conditioning). And to keep themselves smelling like, well, nothing.
As we've established, opossums aren't great at protecting themselves in a standoff with a predator, so it behooves them to keep odor-neutral. Part of the reason opossums have the reputation for being smelly has to do with their other defense mechanism: the smell of death. Once an opossum goes into its theatrical coma, if the predator continues to mess with it, it excretes a smelly mucus from its butt that signals "Hey, this opossum is definitely dead – possibly so entirely dead that it'll make you sorry you ate it."
Opossums Have, Uh, Interesting Reproductive Anatomy
Early Europeans in the New World were confused about opossum reproduction. Their story was that the male opossum mated through the female opossum's snout, which led to her sneezing out her babies into her marsupial pouch. Of course, this is just a legend, but opossums definitely do things a little differently.
First of all, a male opossum has a forked penis (thus the early idea that this was perhaps meant for the female's nostrils) to accommodate the female's double vagina and twin uteri. Opossum embryos develop for about 13 days until they're large enough to migrate down the birth canal and emerge about the size of houseflies. Although dozens of them will be born, the mother only has 13 teats, so that's how many will be able to ride that gravy train into opossum adulthood.
Learn more about opossums in "Awesome Opossum: Everything you wanted to know about Opossums!" by Sparkles. HowStuffWorks picks related titles based on books we think you'll like. Should you choose to buy one, we'll receive a portion of the sale.