The terms “opossum” and “possum” are frequently used interchangeably, blurring the distinction between two groups of marsupials found on separate continents. Both animals are mammals that raise their underdeveloped young in a pouch, but their shared characteristics end there. Scientifically and geographically, the creatures referred to by these similar names are distinct species with unique evolutionary histories. The differences in their taxonomy, physical features, and behaviors demonstrate a biological separation.
Clarifying the Terminology
The naming distinction lies in the animals’ geographic origin and scientific classification. “Opossum,” spelled with the initial “O,” refers exclusively to species native to the Americas, belonging to the Order Didelphimorphia. This group comprises over 100 species found throughout North, Central, and South America. In the United States, the common practice is to drop the initial letter, colloquially referring to the Virginia Opossum as simply a “possum.”
Conversely, the term “possum,” without the “O,” is the correct name for the marsupials found in Australia, New Guinea, and surrounding islands. These animals belong to the Order Diprotodontia, a vast group that also includes koalas and kangaroos. This taxonomic split means the Australian possum is far more closely related to a koala than it is to the American opossum. The original Australian species was named “possum” by early explorers because of its perceived resemblance to the American animal.
Characteristics of the North American Opossum
The North American opossum, Didelphis virginiana, is the only marsupial found north of Mexico. This species is characterized by a grizzled grayish-white coat and a pointed snout. The opossum possesses 50 teeth, which is the highest number of any land mammal in North America.
The opossum is easily identified by its long, hairless, and scaly prehensile tail, which it uses to grasp branches and stabilize itself while climbing. Its hind feet also feature an opposable, clawless toe, known as a hallux, which acts like a thumb to aid in climbing. They are primarily solitary, nocturnal, and terrestrial animals.
One of the opossum’s most well-known defense mechanisms is “playing possum,” or tonic immobility. When severely threatened, the animal enters a coma-like state that can last for minutes or hours. The opossum will stiffen, drool, and emit a foul-smelling secretion from its anal glands, mimicking the scent of a deceased animal to deter predators.
The opossum’s diet is omnivorous, consisting of fruits, insects, small animals, and carrion. This varied diet has led to a natural resistance to the venom of pit vipers, such as rattlesnakes and cottonmouths. Research has identified a peptide in their blood that can neutralize these toxins. This adaptation allows the opossum to survive bites that would be fatal to other similarly sized mammals.
Distinguishing Features of Australian Possums
Australian possums belong to the Suborder Phalangeriformes, which includes approximately 70 species. The most commonly encountered species are the Common Brushtail Possum and the Common Ringtail Possum. Unlike their American counterparts, Australian possums generally have more rounded faces, larger eyes, and fluffier fur, often giving them a bear-like appearance.
Their tail is typically covered in thick fur, especially in the Brushtail Possum. The Ringtail Possum has a tail with a distinctive white tip and uses it like a fifth limb to climb and curl around branches. These marsupials are highly arboreal, spending the vast majority of their lives in trees and only venturing to the ground to move between feeding areas.
Australian possums are primarily herbivorous, feeding on eucalyptus leaves, nectar, flowers, and fruits. Some species will also consume insects or bird eggs. The Common Ringtail Possum has a specialized digestive process where it consumes its own fecal pellets to maximize nutrient extraction from plant matter.