The order Phalangeriformes encompasses approximately 70 species of arboreal marsupials, including possums, gliders, and cuscuses, native primarily to Australia, New Guinea, and Sulawesi. These nocturnal animals inhabit a wide range of vegetated environments, from dense forests to urban parks. The suborder exhibits a remarkable span of dietary strategies, meaning there is no single answer to what they eat. Their feeding habits range from highly adaptable omnivores to extreme specialists whose survival depends on particular plant exudates or toxic foliage. This diversity reflects the varied ecological niches these marsupials occupy across their extensive geographic range.
Generalist Omnivores: Diverse Foraging Strategies
The Common Brushtail Possum (Trichosurus vulpecula) is the prime example of a generalist omnivore within Phalangeriformes, possessing a highly flexible and opportunistic feeding strategy. Although primarily herbivores consuming large quantities of plant matter, their diet regularly includes a significant animal protein component. This adaptability allows them to thrive in numerous habitats, from native woodlands to human-modified urban settings.
Brushtail Possums consume a wide variety of plant parts, including leaves, flowers, shoots, fruits, and seeds. They prefer certain leaves, such as those from Eucalyptus trees, but do not rely on them exclusively. Their rounded molar teeth are suited for grinding a mixed diet, but they are not specialized enough to finely cut tough, fibrous eucalyptus leaves.
To supplement their plant-based energy sources, Brushtail Possums actively forage for animal matter. This protein intake includes invertebrates like insects and spiders, as well as the eggs and young of small birds. This broad spectrum of food allows them to maintain a balanced nutrient profile throughout the year, even when seasonal plant resources are scarce.
In urban environments, their foraging strategies shift to include human-related food sources. They raid fruit trees, vegetable gardens, compost bins, and garbage cans. This omnivorous flexibility, combined with their ability to live close to humans, has made the Common Brushtail Possum one of the most widely distributed marsupials in Australia.
Specialized Consumption: Nectar, Sap, and Gums
A distinct group within the Phalangeriformes specializes in liquid and semi-liquid high-sugar diets, relying heavily on plant exudates for energy. Species like the Sugar Glider (Petaurus breviceps) and Pygmy Possums (Cercartetus species) are adapted to this energy-rich, yet protein-poor, food source. These animals rely on nectar, sap, gum, and insect exudates such as honeydew and lerp.
The Sugar Glider is an omnivore that exhibits a seasonal feeding pattern, switching focus depending on the availability of flowering plants. When flowers are abundant, they consume simple sugars from nectar for immediate energy. They also rely on complex carbohydrates found in plant gums, such as those from Acacia and Eucalyptus, which may constitute up to half of their diet seasonally.
To process these fibrous gums, the Sugar Glider possesses an enlarged caecum, a section of the hindgut that acts as a fermentation chamber. This adaptation allows symbiotic microbes to break down complex polysaccharides in the gums, making the energy available. To access tree sap, gliders use sharp lower incisors to strip bark or open holes in the cambium layer of trees.
Pygmy Possums also utilize specialized anatomical features to access these liquid foods. The Long-tailed Pygmy Possum, for instance, possesses large, forward-pointing lower incisors adapted for scraping or piercing surfaces. These dental tools access sugary fluids and manipulate small arthropods. Both gliders and pygmy possums supplement this high-carbohydrate diet with protein from insects and pollen, which is important for breeding females.
Primary Plant Matter: Foliage and Fungi
Other members of the suborder, such as the Common Ringtail Possum (Pseudocheirus peregrinus), focus their diet heavily on solid, fibrous plant matter, primarily tree leaves. These folivorous species face the dual challenge of low nutrient density and potent plant defensive chemicals, particularly in Eucalyptus foliage. This reliance on tough leaves necessitated the evolution of complex digestive mechanisms.
Ringtail Possums consume large quantities of Eucalyptus leaves, but they are selective, choosing foliage with lower concentrations of toxins like formylated phloroglucinol compounds (FPCs). To extract nutrients from this fibrous material, the Ringtail Possum relies on hindgut fermentation. They possess a greatly enlarged caecum, which functions as a specialized fermentation vat where microorganisms break down cellulose and other plant fibers.
The digestive process is further optimized by the practice of caecotrophy. The animal re-ingests soft, moist fecal pellets produced in the caecum, allowing the partially digested food to pass through the gut a second time. This salvages nutrients, particularly B-vitamins and microbial protein, that were previously unavailable, serving as a refined adaptation to a nutritionally demanding diet.
Beyond foliage, these marsupials incorporate other solid plant materials into their diet, including flowers, fruits, and fungi, depending on seasonal availability. Fungi, or truffles, are often sought out as a source of bulk and specific nutrients, especially by species that forage on the ground.