There are several dozen different species of opossum, which are often called possums in North America. The most notable is the Virginia opossum or common opossum—the only marsupial (pouched mammal) found in the United States and Canada.
A female opossum gives birth to helpless young as tiny as honeybees. Babies immediately crawl into the mother's pouch, where they continue to develop. As they get larger, they will go in and out of the pouch and sometimes ride on the mother's back as she hunts for food. Opossums may give birth to as many as 20 babies in a litter, but fewer than half of them survive. Some never even make it as far as the pouch.
Opossums are scavengers, and they often