Opossum

Opossum, common name for any of 77 marsupial mammals found only in the Western Hemisphere. The opossum ranges in length from 17 to 104 cm (7 to 41 in), including the tail, which is from 9 to 54 cm (4 to 21 in) long. The common Virginia opossum is the largest of the opossums, measuring 109 cm (43 in), of which one-half is tail. The front feet have five toes with claws; on the hind feet the outer four toes bear claws, and the inmost toe is opposable, like a thumb, and nailless. The Virginia opossum is covered with long, sleek, white hair and an undercoating of soft, woolly fur. It has a pointed, slender face and large, broad, naked ears. An opossum has 50 teeth. Most species are omnivorous, usually preferring a diet of insects and carrion. They are nocturnal, sleeping in a burrow during the day and hunting food at night; most are arboreal. The yapock, or water opossum, of South America is aquatic, having webbed hind feet for swimming. The Virginia opossum's habit of feigning death when threatened has given rise to the expression “playing possum.”

Most species have the abdominal pouch characteristic of marsupials; however, in some South American species this pouch is rudimentary or absent. A female opossum may have as many as 17 nipples within the pouch, but 13 is the usual number. From 4 to 24 young opossums, called joeys, may be born in a litter. Of these, only 8 or 9 usually survive. The gestation period is about 13 days, and the newborn opossums, about 1.4 cm (about 0.55 in) long and weighing about 0.16 g (about 0.0056 oz), are quite undeveloped. They must spend about two months in the mother's pouch attached to the nipples before they are able to move about.

The Virginia opossum, found throughout the eastern United States and occasionally in the Western states, is edible and was once considered a delicacy in the South. Opossum fur formerly had commercial value but is little used now. The name opossum is frequently shortened to possum, although the name possum is also used in reference to certain Australasian marsupials unrelated to opossums.

Scientific classification: Opossums make up the family Didelphidae, of the order Marsupialia. The common Virginia opossum is classified as Didelphis virginiana, the yapock as Chironectes minimus.