The terms “possum” and “opossum” often create confusion, though they refer to distinct groups of marsupials. While the names sound alike, they actually designate distinct groups of marsupials found on different continents. These creatures, despite their shared classification as marsupials, have evolved independently in separate parts of the world, developing unique characteristics suited to their environments.
Understanding the North American Opossum
The North American opossum, Didelphis virginiana, is the only marsupial species native to North America. These animals are roughly the size of a domestic cat, typically weighing between 4 and 15 pounds, and possess coarse, grayish-white fur, a pointed snout, and large, hairless ears. A distinctive feature is their long, prehensile tail, used for gripping branches and balance. Opossums are nocturnal omnivores, consuming a varied diet of insects, small animals, fruits, and carrion. They are also known for their involuntary defense mechanism of “playing possum,” where they enter a catatonic state when threatened.
Getting to Know the Australian Possum
In contrast, the term “possum” generally refers to a diverse group of marsupials primarily found in Australia, New Zealand, and surrounding islands. This group includes numerous species, such as the common brushtail possum and the common ringtail possum. Australian possums are typically arboreal, living mostly in trees, and vary significantly in size and appearance. For instance, the common brushtail possum has thick, woolly fur that can range from silver-grey to black, and a bushy tail, while the common ringtail possum is smaller, usually grey-brown, with a distinctively curled, prehensile tail often tipped with white. Their diets also vary by species, generally including leaves, flowers, fruits, and sometimes insects.
Beyond the Name Distinguishing Features
A primary distinction between the North American opossum and Australian possums lies in their geographical distribution; opossums inhabit the Americas, while possums are found in Australasia. The Virginia opossum typically has a more rugged appearance with a scaly, mostly hairless tail and a pointed face. Australian possums, like the brushtail, often exhibit softer, denser fur and a bushier tail. Behaviorally, both are nocturnal, but the North American opossum is renowned for its “playing dead” defense, a trait not typically seen in Australian possums. Their diets also differ; the North American opossum frequently scavenges, whereas Australian possums are often more specialized, with many species primarily eating leaves and plant matter.
A Look at Evolutionary Connections
Both opossums and possums are marsupials, sharing a very distant common ancestor within the infraclass Marsupialia. However, their evolutionary paths diverged millions of years ago, with American opossums belonging to the order Didelphimorphia and Australian possums to various orders, such as Diprotodontia. Marsupials originated in South America, with some migrating to North America and others dispersing across Antarctica to Australia before the continents separated. The similarities in appearance and some behaviors between these geographically separated groups are a result of convergent evolution. This occurs when unrelated species develop similar traits by adapting to comparable environments, rather than from close genetic kinship. Therefore, despite the similar names and shared marsupial heritage, the North American opossum and Australian possums are not closely related in a recent evolutionary sense.