Opossums are unique marsupials, recognized as the only native marsupial found north of Mexico. This article details their distinctive physical characteristics.
General Physical Characteristics
Opossums have a body size comparable to a domestic cat, measuring approximately 15 to 20 inches long (excluding their tail) and weighing between 4 and 12 pounds. Their body is stout, covered in coarse fur. The most common coloration is grayish-white, often with darker guard hairs that give a grizzled appearance. They often have a white face that contrasts with their darker body fur. Opossums exhibit a low-slung posture, often appearing to waddle as they move.
Unique Anatomical Features
Opossums have a long, scaly, nearly hairless tail, which can be almost as long as its body, ranging from 9 to 20 inches. This prehensile tail can grasp and coil around objects, aiding climbing and maintaining balance on branches. While young opossums may briefly hang by their tails, adults are too heavy for this and primarily use their tails for stability or to carry nesting materials.
The opossum’s head has a long, pointed snout and a triangular shape. Their ears are thin, prominent, and hairless. Their hind feet feature a clawless, thumb-like opposable innermost toe. This specialized digit functions much like a human thumb, allowing them to grasp branches and objects, aiding climbing.
Variations in Appearance
Opossum appearance can vary across different species and geographical regions. The Virginia opossum (Didelphis virginiana) is the most widespread species in North America, but other species exist further south, such as the Common opossum, which may have darker fur and more prominent black ears. Regional differences within the Virginia opossum can include variations in fur color, with some populations exhibiting a black phase more commonly seen in the southern United States.
Size can also differ, with larger individuals found in more northern parts of their range. As opossums age, their appearance changes; newborns are hairless, and their fur develops and becomes thicker and coarser with maturity. Older individuals may show signs of wear, such as ragged ears or stubby tails due to frostbite.
Identifying a Possum: Key Distinctions
Distinguishing an opossum from other small mammals, such as large rats, involves observing key visual characteristics. Opossums are significantly larger than most rats, often weighing several pounds, whereas rats weigh less than one pound.
A major differentiating factor is their tail: while both have relatively hairless tails, an opossum’s tail is notably thicker, longer, and prehensile, used for gripping, unlike a rat’s tail which is primarily for balance. Opossums have a distinctive white face with a pointed snout, contrasting sharply with the uniform fur color of rats, which often have pointed but less prominent snouts. Opossums also have prominent, hairless ears and unique hind feet with an opposable, thumb-like toe, features not found in rats.