The term “possum” is often used broadly, leading to confusion when people encounter various nocturnal mammals. Several different species share superficial physical traits, such as a similar size, a grayish coat, and a long tail. A linguistic accident also links the North American animal to Australian marsupials, further complicating identification.
The Virginia Opossum: Establishing the Baseline
The animal most people in North America refer to as a possum is the Virginia Opossum (Didelphis virginiana), the continent’s only native marsupial. This mammal typically reaches the size of a large house cat, weighing between 4 and 14 pounds. Its coat is a coarse mix of gray and white fur, set against a long, pointed snout.
Physical features unique to the opossum include its hairless, scaly tail, which is prehensile and used for grasping branches and balance while climbing. Another hallmark is the opposable thumb (hallux) found on its rear feet, which aids in arboreal movements.
North American Animals Often Confused
Several common North American mammals are frequently mistaken for the Virginia Opossum due to their nocturnal habits and general size. The Raccoon (Procyon lotor) is a common look-alike, often foraging in suburban areas. Raccoons are distinguished by their iconic black facial mask and their bushy tail marked with dark rings. The Raccoon’s build is stockier, and its tail is not prehensile.
Another animal causing confusion is the Groundhog, or Woodchuck (Marmota monax), which has a stout, compact body and short, powerful legs. Unlike the opossum’s pointed face, the groundhog has a rounder face, smaller ears, and a short, bushy tail.
Juvenile opossums are sometimes confused with large rodents, particularly the Norway Rat (Rattus norvegicus). While both have a pointed snout and a long, scaly tail, a young opossum retains the opposable thumb on its hind foot and has a disproportionately large head. The adult Norway Rat is significantly smaller, and its tail lacks the prehensile function.
The Australian Possum: A Separate Species
The Australian possum, such as the Common Brush-tailed Possum (Trichosurus vulpecula), is a completely different animal despite the shared name. The confusion is linguistic, dating back to early European exploration when the Australian marsupial was named for its perceived similarity to the North American opossum. Taxonomically, the two belong to separate mammalian orders: Didelphimorphia (North American) and Diprotodontia (Australian).
The Australian possum is far less rat-like than its American counterpart. It features a furrier, often bushy tail, and has thick, soft fur covering its entire body, including its ears. Australian possums also possess a shorter, less pointed snout, giving them a softer, more squirrel-like facial profile. The species is native only to Australia and surrounding islands.
Quick Identification Checklist
Distinguishing an opossum from a look-alike can be achieved by focusing on three key physical characteristics. First, observe the tail, the most telling feature. The opossum has a long, hairless, scaly tail used for grasping, unlike the bushy, ringed tail of a raccoon or the short, furred tail of a groundhog.
Second, look closely at the ears and snout: Opossums have thin, naked, black ears and a long, narrow snout, while raccoons have small, rounded, fur-covered ears and a mask-like face, and groundhogs have a broad, blunt snout. Finally, check for the opposable thumb on the hind foot, a unique marsupial trait that aids in climbing and is absent in raccoons and groundhogs.