There are about 75 species of American marsupials (pouched mammals), all of which are called opossums. These are divided into 3 family groups: American opossums, shrew opossums, and the colocolo or Monito del Monte. American opossums are "true" opossums. They range in size from one species about as small as a mouse to the cat-size Virginia opossum. Most are omnivores (animals that eat both animal and plant foods) and are able to climb. Those that spend more time on the ground than in trees have shorter tails and eat more meat than the tree opossums. Opossums are not afraid to live near humans and sometimes become pests in orchards.
The yapok, or water opossum (Chironectes minimus), is the only true amphibious marsupial, living half its life in water and half on land. The female gives birth to 5 to 6 young. By tightening her muscles she makes her pouch watertight and takes her babies swimming with her as she hunts for food in freshwater lakes and streams. The yapok has webbed back feet that paddle wih a running motion. Because its eyes are shut tight while it is under water, the yapok feels for soft animals at the bottom of freshwater lakes and streams with its sensitive fingers. The 7 species of shrew opossum live in the cool, misty forests of Andes Mountains in South America. They are the size of mice or rats. Two long incisors (cutting teeth) stick forward from their bottom jaw and are used to stab the large insects and small animals upon which they prey.
The colocolo, also called American spotted cat (Leopardus colocolo), and monito del monte ("little monkey of the mountain"), lives in the cool rain forests of southern Chile in South America. Natives of the Lake Region of Chile believe that seeing this rat-size opossum brings bad luck.
Small Australian Marsupials count about 200 species. They can be divided into 4 groups: the carnivorous marsupials (meat-eaters); the marsupial mole; the bandicoot group; and the large group of diprotodonts, which includes koalas, wombats, possums, and kangaroos. The 3 families of meat-eating marsupials have 3 or 4 pairs of narrow, pointed incisors on their upper jaw and 3 pairs on their lower jaw. Their hind feet have 4 or 5 toes. The Tasmanian devil, the Tasmanian tiger, and the numbat belong to this group.
All bandicoots are omnivores. Small species are rat-size, and larger species are as big as badgers. They are well known - in fact, notorious, as carriers of ticks. Bandicoots use their strong front claws to burrow for insects, larva and the succulent parts of plants that grow underground.
More than half of all Australian marsupials belong to Diprotodont group of mammals. They have only 1 pair of well-developed incisors in their lower jaw. The three living species of wombat belong to the diprotodont group. They look like miniature bears, but are very timid and eat only grass. Wombats are nocturnal and live in large burrows.
The koala is a distant relative of the wombat. It has long arms and legs and almost no tail, and for its size it has a remarkably small brain.
Cuscuses and the scaly-tailed possum have strongly prehensile tails. The brushtail possum is the most common type of possum found in Australia. Ringtails possums are so called because of their long, slender, prehensile tails, which they carry tightly curled when not in use. All species except the rock ringtail live in trees.
The cat-size greater glider has a membrane that stretches between the elbow and ankle on each side of its body. It uses this as parachute to glide from tree to tree. The greater glider has been recorded traveling distances of over 300 feet in this way.