Several animals are referred to as “harbingers of spring,” but opossums aren’t one of them.

However, except for when Ice Age events periodically changed the climate across much of North America, one fact of Nature has been pretty much a sure thing for the past 70 million years: When opossums start having young, spring is on its way.

Opossums – or “possums” as they’re usually called – evoke several emotions from humans, but admiration is rarely one of them. Many people find their sneering facial expression disgusting and their overall appearance repulsive.

However, even ardent ’possum-haters should tip their hats to this animal for its longevity. Opossums are one of the world’s oldest mammals. Fossil records show they’ve been around since the Upper Cretaceous Period – a time when dinosaurs were still common.

Opossums are North America’s only marsupials, which mean they are the New World’s closest relatives to kangaroos and koalas. Like other marsupials, opossums have a marsupium – a pouch. From late February through much of March, female adult opossums put their marsupiums to use because this is when they have the first of two annual litters (the second is in late May-early June). Newborn opossums have well-formed claws on their front legs they use to climb up their mother’s body into her marsupium. Female opossums normally have 13 teats in their marsupiums, but often have litters of more than 13. To compound the problem of too many offspring for not enough feeding locations, some teats are smaller than others and don’t get used. As a result, the average number of young an opossum usually ends up carrying in its pouch is around nine. At 80 days of age, the young begin to leave the pouch for short periods. When the young become too large for their mother’s pouch, they frequently ride on her back for approximately the next three weeks.

Opossums are the only North American mammals with prehensile tails. They are also immune to the venom of copperheads, rattlesnakes, cottonmouths and a number of other venomous snakes.

Perhaps the opossum’s most interesting trait is its habit of “playing ’possum.” This self-defense mechanism involves a cornered opossum feigning death by rolling on its side, becoming limp, shutting its eyes and letting its tongue hang out. The heart rate also slows. It’s not certain if this is an intentional act or an uncontrolled reaction – a wildlife version of fainting. Either way, it recovers quickly and is able to take the first opportunity to escape.

Opossums are omnivores. Insects and carrion are common food items, but they also eat small mammals, worms, snails, slugs, bird eggs, fruits and some grains. Their eating can cause occasional problems for humans, but studies have shown they aren’t the nuisances to us that they’re often portrayed as being.

Opossums are classified as game animals in Missouri and are included in the winter furbearer season (see the Wildlife Code of Missouri for hunting and trapping details). Opossum fur is used chiefly to trim inexpensive cloth coats. Opossums can also be hunted in season for table fare, although few people do this anymore.

More information on opossums is at mdc.mo.gov.