Here's why:
* Playing Dead: When threatened, opossums will go limp, drool, and even emit a foul odor. This makes them appear dead and unappealing to predators, who are often deterred by carrion.
* Rotten Smell: The opossum has a pair of anal glands that secrete a pungent, musky odor that smells like rotting flesh. This odor is particularly strong when the opossum is stressed or frightened.
This combination of playing dead and smelling rotten is a highly effective defense mechanism that helps opossums survive encounters with predators.