An opossum is a small, nocturnal animal famous for its ability to play dead when threatened by predators. Opossums are marsupials, which means mothers carry their babies in a pouch.
Opossums are also called possums, and the colloquial phrase used when they play dead is "playing possum." These omnivorous, cat-sized mammals often get a bad rap, thought of as dirty, hissing creatures that lurk around your garbage cans at night. In reality, opossums are very clean and highly social. They also perform the important task of fighting Lyme disease: one opossum can eat as many as 5,000 ticks each year.