Why Do Opossums Play Dead? How Playing Possum Really Works

What happens when an opossum plays dead?

The scientific name for playing dead is thanatosis, or tonic immobility. In the Virginia opossum, the response looks dramatic. The animal rolls onto its side and lies stiff or limp, with its mouth open, lips pulled back to show its teeth and the tongue often hanging out. The eyes may stay open with a fixed stare.

Saliva drips from the mouth, and the feet are often curled. At the same time, glands near the anus release a greenish, foul-smelling fluid. Together, the pose, the drool and the smell make the opossum look and smell like an animal that has been dead for some time.

Breathing becomes slow and shallow, and the opossum ignores prodding, so a predator can nudge it, sniff it or even carry it without getting a reaction. Despite this, studies of opossums in this state suggest the animal is not unconscious. It seems to stay aware of what is happening around it while its body is locked into stillness.

Is playing dead a choice or a reflex?

The phrase “playing” possum suggests a clever act, but the response is not a deliberate performance. Biologists consider it an involuntary reaction that switches on when the animal is overwhelmed by fear, similar to the way some people freeze in shock.

Because it is automatic, an opossum cannot end the state at will while the threat is still close. When things go quiet, it slowly lifts its head, sniffs and listens, and only then gets up and walks away. The whole episode can last from about a minute to several hours, with the longest reported cases reaching around six hours.

The response is also less common than its fame suggests. According to field observations, adult opossums more often stand their ground with a bluff or run away. Young opossums are the most likely to collapse and play dead.

Why does playing dead work against predators?

Playing dead works because many hunters are triggered by movement. Dogs, coyotes, foxes and bobcats are geared to chase and kill struggling prey. When the prey suddenly stops moving, a predator may relax its grip, lose interest or move away to check on something else, giving the opossum a chance to slip off.

The foul smell adds another layer. Many predators avoid eating meat that seems to be rotting, since spoiled flesh can carry disease. To a hunting animal, a drooling, stinking, motionless opossum looks like a poor meal.

It can also defuse confrontations with animals that are not hunting at all. A large mammal guarding its young, or a dog that is simply curious, may ignore an opossum that appears harmless and dead.

The defense is not perfect. Scavengers that happily eat carrion, and predators that kill first and check later, will still eat an opossum. On roads, freezing in fear in front of oncoming cars is often fatal, one reason so many opossums die in traffic.

What other defenses do opossums use?

Before collapsing, an opossum usually tries to look dangerous. It turns to face the threat, opens its mouth wide to show its 50 teeth, hisses, growls, screeches and drools. The fur may stand on end so the animal looks bigger. This bluff is often enough to make a dog or cat back off.

Opossums can also escape by climbing. Their gripping tail and clawless, thumb-like big toes on the hind feet make them good climbers, and they often head up a tree or fence when chased. They can swim, too, and on the ground they can make quick turns to dodge a pursuer, even though their top running speed is only about 7 km/h (4.5 mph).

If cornered, an opossum may bite in self-defense, so the drooling, open-mouthed display should be taken as a clear request to be left alone. It is not a sign of rabies, which is rare in opossums.

Do other animals play dead?

Playing dead is widespread in the animal kingdom. The eastern hognose snake of North America is famous for rolling onto its back, opening its mouth and releasing a bad smell when threatened. Europe’s grass snake does much the same, lying belly-up with its mouth open and tongue hanging out.

Many insects drop and freeze when disturbed, including weevils, ladybugs and stick insects, which add stillness to their camouflage, as described in how do stick insects hide?. Some spiders, frogs, birds and fish show similar tonic immobility. The opossum is simply the most familiar example in North America, which is why the behavior is named after it.

Where does the phrase “playing possum” come from?

The expression “playing possum” has been used in American English since at least the 19th century. It means pretending to be dead, asleep or unaware in order to deceive someone, from a child faking sleep to a sports team hiding its true strength.

The phrase comes from Americans’ long familiarity with the Virginia opossum, often simply called a possum. For more on the animal behind the expression, including what it eats and how its young ride on the mother’s back, see the Virginia opossum profile and our guide to possum vs opossum.