While often confused, “opossum” and “possum” refer to distinct marsupials from different parts of the world. The Virginia Opossum, commonly called “possum” in North America, is the continent’s only native marsupial. True possums are a diverse group found predominantly in Australia and surrounding regions. This article clarifies their differences in naming, physical characteristics, behavior, and shared marsupial traits.
Understanding the Names
The term “opossum” refers to marsupials of the order Didelphimorphia, primarily found in the Americas. The Virginia Opossum (Didelphis virginiana) is the most well-known species, inhabiting North and Central America. This animal is the original “opossum,” a name derived from an Algonquian word.
Conversely, “possum” is the common name for a variety of marsupials of the order Diprotodontia, native to Australia, New Guinea, and nearby islands. Examples include the Common Brushtail Possum (Trichosurus vulpecula) and the Common Ringtail Possum (Pseudocheirus peregrinus). Early European settlers in Australia named them “possums” due to a superficial resemblance to American opossums, despite their distinct evolutionary paths.
Key Physical and Behavioral Distinctions
American opossums and Australian possums show notable physical differences. The Virginia Opossum typically has coarse, grizzled gray fur, a pointed white face, large hairless ears, and a long, scaly, prehensile tail. They average between 1.7 and 14 pounds and measure 13 to 37 inches from head to tail base.
Australian possums often possess softer, denser fur, which can vary widely in color from silver, grey, and brown to black or reddish hues. Species like the Common Brushtail Possum have bushy tails, while Ringtail Possums have long, tapering tails with a white tip, often furred, and also prehensile. Australian possums are generally smaller than their American counterparts, with many species being cat-sized or even mouse-sized.
Behaviorally, a distinct difference is the Virginia Opossum’s involuntary “playing dead” response, also known as thanatosis. When severely threatened, the opossum enters a catatonic state, becoming limp, with open mouth and eyes, and may even emit a foul-smelling fluid. This behavior is not characteristic of Australian possums, which are primarily arboreal and often seek refuge in tree hollows or dense foliage.
Common Marsupial Characteristics
Despite their geographic and physical distinctions, both opossums and possums share fundamental characteristics as marsupials. They are both pouched mammals, meaning females possess a marsupium, or pouch, where their underdeveloped young continue to develop after birth. Marsupials have a short gestation period, typically ranging from 12 to 40 days, after which the tiny young crawl into the mother’s pouch to attach to a nipple and complete their development.
Both groups are generally nocturnal, meaning they are most active during the night. Their diets are largely omnivorous, consuming a variety of insects, fruits, grains, and small vertebrates, though specific dietary preferences can vary between species. Many species in both the American opossum and Australian possum groups also possess prehensile tails, which they use for grasping branches and aiding in climbing. These shared traits reflect their common evolutionary heritage within the infraclass Marsupialia.