Opossums are at greatest risk from humans, domesticated pets, and cars. Often, an opossum mother killed by a car will have uninjured babies in her pouch. Opossums that survive until adulthood usually live only 1 to 2 years.
Opossums are North America's only marsupial (pouched mammal) and have been around for 70 to 80 million years; this makes them one of the Earth's oldest surviving mammals.
The female carries and nurses her young in her pouch until they are about two to three months old; then they are carried on her back another 1 to 2 months whenever they are away from the den. An opossum mother may carry as many as thirteen babies in her pouch. Babies are most common between February and June.
Opossums have opposable thumbs on their rear feet and can also grasp with their tails. They are one of the shortest lived mammals for its size. They are killed by many predators: humans (and cars), dogs, cats, owls, and larger wildlife.