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Last updated on April 19, 2014 at 9:20 EDT

Virginia Opossum, Didelphis virginiana

The Virginia opossum (Didelphis virginiana) is the only marsupial that occurs north of Mexico in North America. It is commonly known as the North American opossum and as “tlacuache” in Mexico. It is often seen in or near human settlements, foraging through waste for food.  Its range includes Central and North America, east of the Rockies, and from Costa Rica to southern areas of Ontario, Canada. It has been found farther north than Toronto and in northwestern Minnesota, and so it is though that is range is still growing. It was introduced into the Pacific Coast area during the Great Depression, most likely as a food source.

The word “opossum” derives from the Algonquian word wapathemwa, which means “white animal”. In Virginia, this animal is colloquially known as the possum, although it is the original “opossum”.  The name “possum” is used to denote many species in the Didelphimorphia and Paucituberculata orders, as well as possums in Australia, although these are in the order Diprotodontia.

The Virginia opossum can vary in size depending upon location. Larger individuals are found most often in the northern areas of the species’ range, while individuals in southern tropical areas are smaller. The average body length of this species is between 13 and 37 inches, with a tail length that can range between 8.5 and 19 inches. Weight varies between locations as well as with sex, with males weighing as much as 14 pounds, and females weighing as much as 8.2 pounds. Because of the varied size differences between individuals, the Virginia opossum is known as one of the world’s most variable species.

The fur of the Virginia opossum is generally greyish brown, with the exception of the white fur on its elongated face. These animals have fifty teeth, the most out of all North American mammals. It bears opposable thumbs on its hind limbs that lack claws.

The tracks made by the Virginia opossum have been well studied, and are typically seen with five, finger-like markings. These prints are distinctive in that the thumbs usually leave a ninety-degree angle, sometimes 180 degree, a trait that is unique to these possums. Adult tracks can measure 1.8 inches by 2 inches in the fore feet, and 2.5 inches by 2.2 inches in the hind feet. The claws that appear on all toes, excluding the thumbs, do not always appear in the tracks.

The pattern of the tracks will vary depending on the pace that the opossum was moving in when it made them. In a pacing gait, the most commonly used in this species, the right forefoot and left hind foot fall together, and vice versa.  Other animals like bears, raccoons, and beavers use this gait to travel as well. The stride of this possums gait usually measures between seven and ten inches.

The Virginia opossum is known for its ability to “play dead”, a defense mechanism used when it feels threatened or is injured. The term “playing possum” derives from this behavior. The opossum does not implement this defense voluntarily, and it is thought it occurs in situations of extreme danger. When encountering a lesser yet still dangerous threat, the opossum will screech, hiss, and bear its teeth and can be harmful. If it is frightened enough, it will enter a near coma state, lying on its side and lolling its tongue out if its mouth. It will also secrete an odor from its anus that deters both predators and potential prey from thinking it is alive.

The Virginia opossum is omnivorous, feeding on many things like fruit and small animals. In the fall season, wild individuals show a great preference for persimmons. In captivity, some cannibalism has been recorded, so it is not advised that an injured opossum be placed in the same areas as a healthy individual. Although this possum does not hibernate, it will move into a shelter during colder months.

In 1608, John Smith described a possum in his Map of Virginia, with a Description of the Countrey, the Commodities, People, Government and Religion, stating its similarities to a rat, pig, and cat. It was more thoroughly and formally described in 1698, in a letter called “Carigueya, Seu Marsupiale Americanum Masculum. Or, The Anatomy of a Male Opossum: In a Letter to Dr Edward Tyson,” written by Mr. William Cowper. This letter alluded to past descriptions as well.

Most interactions of the Virginia opossum with humans are related to the foraging habits of the animal. Because it is often seen digging though garbage, it is confused with a rat, but it is not related to rodents in any way. Although it can be dangerous to humans, it does not often transmit diseases like rabies, and it is known to prevent the spread of Lyme disease because it kills the pests that carry it. In its southern range, it is a popular form of food, and there are many recipes that include possum meat. Common forms of cooking including baking the meat into pies, although the popular “possum pie” does not actually contain any meat.

Even with its large range, the Virginia opossum most commonly appears in southeastern folklore, where it represents uncivilized characters, or “hillbillies”. In one comic called Pogo, written by Walt Kelly, the main character is a possum. In 2010 in Leipzig Zoo, located in Germany, a Virginia opossum named Heidi became internationally known and appeared on a talk show to predict the 2011 Oscar winners. Not all public perceptions of this possum were positive. When the possum was tied to U.S. president William Howard Taft as Billy Possum, the attempt to create another “teddy bear” image failed, as most people considered the possum to be an undesirable animal.

As is typical to most marsupials, the Virginia opossum has a short lifespan in most areas of its range. In the wild, it lives for approximately two years, while in captivity it only reaches around four years of age. It is thought that is short lifespan is a result of a large range, wide distribution across that range, and a lack of natural predators, a tendency to not live long in the first place. The Virginia opossum appears on the IUCN Red List with a conservation status of “Least Concern”.

Image Caption: North American Opossum with winter coat. Credit: Cody Pope/Wikipedia(CC BY-SA 2.5)

Virginia Opossum Didelphis virginiana