- Class: Mammilia
- Order: Didelphimorphia
- Family: Didelphidae
- Genus: Didelphis
- Species: virginiana
Often misunderstood and persecuted by many, opossums actually help keep the environment healthy and tidy by eating dead stuff and lots of disease-carrying ticks. There are over 100 different opossum species, ranging in size from the pocket-sized pygmy opossum to the domestic cat-sized Virginia opossum. This Didelphidae family of marsupials is native to the New World; the Virginia opossum Didelphis virginiana is the only marsupial native to North America.
While opossums are commonly referred to as "possums," the possum is actually a separate creature. Possums include several species of nocturnal, arboreal (tree-dwelling) marsupials native to Australia and New Guinea. The story goes that the name “opossum” was first used in western culture by Captain John Smith in 1608. The word comes from the Algonquin name “aposoum” which means “white beast.” In the late 1700s, Sir Joseph Banks, a naturalist and explorer, likened the furry tree-dwelling marsupials he saw in Australia to “an animal of the Opossum tribe.” Adding to the confusion, the name was later shortened to “possum.” But the opossum and possum are two very different arboreal marsupial families.
"Playing Possum." When threatened or harmed by dogs, foxes, bobcats, or other predators, opossums may "play possum", appearing to be sick or dead. The lips are drawn back, teeth are bared, saliva foams around the mouth, and a foul-smelling fluid is secreted from the anal glands. Although the word “play” suggests a conscious act, this catatonic defense mechanism is actually a completely involuntary and automatic physiological response to danger. It’s more like fainting from fright than pulling a prank on a potential predator.
Many injured opossums have been killed by well-meaning people who find a catatonic opossum and assume the worst. The best thing to do upon finding an injured or seemingly dead opossum is to leave it in a quiet place with a clear exit path. In minutes or hours, the opossum will likely regain consciousness and escape quietly on its own.
I’m Not a Pet. Since opossums have adapted nicely to living among human habitation, sometimes young opossums get “rescued” by the well-intentioned public and raised as a pet. This will likely not bode well for the opossum. As the Opossum Society of the United States points out, it is illegal in most states to keep opossums as pets. Worse yet, sometimes the opossum will become lame as it grows, which is likely due to a diet-induced disorder called Metabolic Bone Disease, or rickets. If you find an injured opossum, it is important to contact your local wildlife rehabilitator where trained professionals can help.
Oh, Possum. Opossums are small- to medium-sized, pouched (most of them) mammals (marsupials, like kangaroos and koalas) with pointed snouts, and nearly hairless tails that are prehensile, as are their hands and feet. The Virginia opossum has a cat-sized body; grey or whitish fur with a white face; long pointy snout; round dark eyes and hairless ears; four paws; long, hairless tail spanning over 1/3 of its total body length. It has a slow, side-to-side gait as it forages for food, usually at night.
HABITAT AND DIET
Cool and Common. The Virginia opossum, also called the North American or common opossum, is the only Didelphis species found north of Mexico. Flexible in habit, this opossum ranges from southern Canada, and south into Nicaragua and Honduras.
Home at Last. Generally, the opossum lives in forests or swamps that get plenty of rainfall, but they are wildly adaptable and able to live among humans in open country as well as urban areas. When not lodging in tree holes or in dens made by other wildlife, they can shelter in sheds, barns, or under homes. They are harmless to humans, so if you discover one living under your house, just let it be. It’s keeping your neighborhood clean! While the opossums may be infested with ticks and fleas, and therefore be vectors for such infestations in your home or on your pets, they can also be key in keeping many diseases at bay.
Sniffing Out Supper. The Virginia opossum’s long muzzle allows its keen sense of smell to detect all sorts of omnivorous delicacies including a wide range of plants, fruits, insects, and other small animals. Even venomous snakes are on the menu! This type of opossum also imbibes in carrion and garbage. They have also been observed near roadkill, a hazardous food source as cars barrel down on them. Cleaning up carrion (dead stuff) has earned them the title Nature’s Little Sanitation Engineer.
Pig Out and Tidy Up. Opossums roam around at night in search of all types of bugs and insects (even cockroaches!), snails, mice, rats. It is estimated that a single opossum can eat 5,000 ticks in a year, thus protecting other wildlife (and humans) from tick-borne diseases like Lyme disease.
Night Moves. The Virginia opossum, usually active by night, demonstrates terrestrial, arboreal, and aquatic locomotion. It is an excellent climber and a decent swimmer. It can only hold on by its prehensile tail for short periods of time, but its handy “fifth hand” is most useful in the trees. It can become more active by day in colder, northern climes. Seeking food takes up much of its time.
Stay Away! Virginia opossums may be predated upon by owls, domestic dogs, coyotes, red foxes, raccoons, bobcats, and large snakes. Their most formidable threat may be humans who hunt and trap them. Vehicle strikes are another danger. In some regions of the US, opossums are hunted for food.
When threatened, opossums run, growl, belch, hiss, urinate and defecate. If protecting they young, add biting to the list. When all else fails, they “play ‘possum" and act as if they are dead. It is an involuntary response (like fainting) rather than a conscious act. They roll over, become stiff, close their eyes (or stare off into space) and bare their teeth as saliva foams around the mouth and exude a foul-smelling fluid. The catatonic state can last for up to four hours, and has proven effective as a deterrent to predators looking for a hot meal.
Listen Up. The opossum uses scent and auditory signals to communicate with their joeys, mates, and potential aggressors. Scent glands help the tiny neonates locate mom’s pouch. Males have sternal scent glands that emit a musky odor and stain their fur prior to mating season. Males can find receptive females by scent. When threatened, they growl and hiss before exuding a rank excretion from their anal glands.
Females keep tabs on their youngsters through a series of clicks, lip smacking and bird-like sounds. Like many other nocturnal wildlife, their hearing is acute. They also have sensitive whisker-like hairs growing around the face and muzzle called vibrissae, which serve as tactile assistance in the dark.
Jack and Jill…and Joeys. The number of annual litters is influenced by the climate: in northern regions, an opossum has just one litter, while opossums in warmer climes may have up to three litters in a year. The male, called a jack, does not stick around to help the female raise the joeys. Gestation is just shy of two weeks. Female opossums, called jills, give birth to up to about 20 tiny live young per litter.
The honeybee-sized joeys promptly crawl into the mother's pouch to continue developing. Many newborns don’t make the journey into the pouch; fewer than half will survive. Those who make it will latch onto a nipple for about 50 to 70 days—on average, females have eight pouch-young per litter.
Piggyback. Even after the joeys can leave the pouch, the devoted mother will still tote them about on her back while she hunts and scavenges for food. The rapidly growing joeys will stay with their mother for about 100 days. Joeys become sexually mature at six to eight months of age and live for two to four years.
Stable. Most opossum populations are stable. By supporting San Diego Zoo Wildlife Alliance, you are our ally in saving and protecting wildlife worldwide.