Opossums, which include the roughly 100 species in the order Didelphimorphia, are some of the most misunderstood animals in the Americas. They’re often thought of as dimwitted, dirty creatures whose most impressive trick is acting like roadkill.

The truth is just the opposite: Opossums are smarter, cleaner, and more beneficial to people than many of their woodland comrades. Read on for more interesting facts about opossums.

1. Opossums and possums aren’t the same animal.

In North America, opossum and possum describe the same animal, but in Australia the word possum refers to a completely different order of organisms. Among the bestknown of their respective types are the Virginia opossum and the brushtail possum. Both are small- to medium-sized, omnivorous marsupials, but the similarities end there. The possum looks like a cute cross between a squirrel and a chinchilla, and it belongs to a different order than the North American mammal that shares (most of) its name.

Despite the potential for confusion, possum is accepted as the shortened version of opossum in this part of the world (and if you see the word possum in this list, you can assume it’s referring to the animal from the Americas).

2. They’re the only marsupials found north of Mexico.

Marsupials—mammals that carry and nurse their young in pouches—are absent from much of the world, and in Canada and the United States, the Virginia opossum (Didelphia virginiana) is the sole representative of the group.

Like other marsupials, mother possums give birth to tiny, underdeveloped offspring (called joeys) that immediately crawl into a pouch where they live and nurse during their first months of life. Only once they’ve grown big and strong enough do they venture out, transitioning between their mother’s back and the warmth of the pouch until they mature into adults.

3. They can’t choose when they “play dead.”

Perhaps the most famous characteristic of the opossum is its tendency to play dead in front of predators. When the animal experiences intense fear in the face of danger, it seizes up and flops to the ground where it can remain for hours staring blankly ahead and sticking out its tongue.

It’s an impressive defensive mechanism, but its effectiveness can’t be chalked up to the possum’s acting skills. Possums have no control over when they play dead or for how long they do it: The comatose-like state is an involuntary reaction triggered by stress.

4. An offensive odor helps sell the performance even more.

A picture of a possum playing dead doesn’t really do it justice. To get the full experience, you need to be standing over to it to smell the putrid odor it emits when pretending to be a corpse. Along with its body going limp, one will appear to stop breathing, discharge its bowels, and release a pungent aroma into the air.

The smelly substance it secretes from its anus is just one more reason for natural predators like foxes and bobcats to look for their dinner elsewhere.

5. They help to slow the spread of Lyme disease.

Even if possums aren’t the cutest creatures in the forest, they should be a welcome addition to your backyard. Unlike other mammals that carry ticks, which may spread Lyme disease, possums gobble up about 90 percent of the ticks that attach to them.

According to the National Wildlife Federation, a single possum consumes 5000 of the parasites per tick season. That means the more possums that are in your area, the fewer ticks you’ll likely encounter.

6. Their memories are surprisingly sharp.

Opossums have impressive memories—at least when it comes to food. Researchers found that possums are better at remembering which runway led to a tasty treat than cats, dogs, and even rats. They can also recall the smell of toxic substances up to a year after trying them.

7. They’re immune to most forms of snake venom.

While most animals look at a snake and see danger, a possum sees its next meal. The animals are immune to the venom of nearly every type of snake found in their native range (including rattlesnakes), the one exception being the coral snake. Possums take advantage of this by chowing down on snakes on a regular basis.

Researchers have been trying to harvest possums’ anti-venom powers for decades. Back in 2015, a team of scientists made progress on this front when they recreated a peptide found in possums and and found that mice given the peptide and rattlesnake venom were successfully protected from the venom’s harmful effects.

8. They almost never get rabies.

While possums aren’t totally immune to rabies (a few cases have been documented), finding a specimen with the disease is extremely unlikely. Marsupials, like possums, have a lower body temperature than the placental mammals that dominate North America—in other words, their bodies aren't suited to the rabies virus.

9. Their tails act like a fifth appendage.

Opossums have prehensile tails. These appendages are sometimes used as an extra arm: They can carry grass and leaves for building nests or grip the sides of trees to provide extra stability while climbing.

Baby possums can even use their tails to hang from branches upside down, as they’re often depicted doing in cartoons. But it’s a myth that possums sleep this way: Their tails are only strong enough to hold them for a short amount of time.

10. They’re constantly self-grooming.

Thanks to their whole acting-and-smelling-like-a-corpse routine, opossums aren’t known as the most sanitary animals in nature. But they take cleanliness seriously: According to the Washington Department of Fish and Wildlife, possums—like house cats—use their tongues and paws to groom themselves frequently and thoroughly.

Possums largely lack sweat glands, so grooming is believed to help them cool down. It also has the added effect of rendering them odorless (when they’re not secreting stinky predator repellent, that is).

11. Their eyes aren’t totally black.

One of the opossum’s most recognizable features is its opaque eyes. Opossum eyes do have whites and irises, but because their pupils are so large, their eyes appear completely black from a distance. The exaggerated pupil dilation is thought to help the nocturnal animals see better after the sun goes down.

12. They’re social creatures.

It was long assumed that opossums like to keep to themselves, but a 2015 study published in the journal Biology Letters suggests they have a social side.

Researchers at the Federal University of Pernambuco in Recife, Brazil, observed some possums in captivity sharing dens even if they weren’t mates. In one case, 13 white-eared opossums of various age groups were cohabiting the same space. The scientists suspect that male and female possums living in the wild may even build nests together as a way to trigger the female’s reproductive hormones.

13. Their reproductive systems are complicated.

The way it gives birth and raises its young isn’t the only thing that’s interesting about the opossum’s reproductive life. Females have two vaginal tracts and two uteri, and males in turn have a forked or bifurcated penis.

This is fairly typical for marsupials, but when European colonizers first landed in North America centuries ago, they didn’t know what to make of the confusing genitalia. One explanation they came up with was that male opossums impregnated females through the nose.

A version of this article was originally published in 2018 and has been updated for 2023.

This article was originally published on www.mentalfloss.com as 13 Facts About Opossums.