Opossum

Opossum, common name for any of 77 marsupial mammals found only in the Western Hemisphere. Opossums make up the family Didelphidae, of the order Marsupialia. The common Virginia opossum is classified as Didelphis virginiana, the yapock as Chironectes minimus. 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.

Classification

 * Family Didelphidae
 * Subfamily Caluromyinae
 * Genus Caluromys
 * Subgenus Mallodelphys
 * Derby's Woolly Opossum, Caluromys derbianus
 * Brown-eared Woolly Opossum, Caluromys lanatus
 * Subgenus Caluromys
 * Bare-tailed Woolly Opossum, Caluromys philander
 * Genus Caluromysiops
 * Black-shouldered Opossum, Caluromysiops irrupta
 * Genus Glironia
 * Bushy-tailed Opossum, Glironia venusta
 * Subfamily Didelphinae
 * Genus Chacodelphys
 * Chacoan Pygmy Opossum (Chacodelphys formosa)
 * Genus Chironectes
 * Yapok or Water Opossum (Chironectes minimus)
 * Genus Cryptonanus
 * Agricola's Gracile Opossum (Cryptonanus agricolai)
 * Chacoan Gracile Opossum (Cryptonanus chacoensis)
 * Bolivian Gracile Opossum (Cryptonanus guahybae)
 * Red-bellied Gracile Opossum (Cryptonanus ignitus)
 * Rio Grande do Sul Gracile Opossum (Cryptonanus unduaviensis)
 * Genus Didelphis
 * White-eared Opossum (Didelphis albiventris)
 * Big-eared Opossum (Didelphis aurita)
 * Guianan White-eared Opossum (Didelphis imperfecta)
 * Common Opossum (Didelphis marsupialis)
 * Andean White-eared Opossum (Didelphis pernigra)
 * Virginia Opossum (Didelphis virginiana)
 * Genus Gracilinanus
 * Aceramarca Gracile Opossum (Gracilinanus aceramarcae)
 * Agile Gracile Opossum (Gracilinanus agilis)
 * Wood Sprite Gracile Opossum (Gracilinanus dryas)
 * Emilia's Gracile Opossum (Gracilinanus emilae)
 * Northern Gracile Opossum (Gracilinanus marica)
 * Brazilian Gracile Opossum (Gracilinanus microtarsus)
 * Genus Hyladelphys
 * Kalinowski's Mouse Opossum (Hyladelphys kalinowskii)
 * Genus Lestodelphys
 * Patagonian Opossum (Lestodelphys halli)
 * Genus Lutreolina
 * Lutrine or Thick-tailed Opossum (Lutreolina crassicaudata)
 * Genus Marmosa
 * Heavy-browed Mouse Opossum (Marmosa andersoni)
 * Rufous Mouse Opossum (Marmosa lepida)
 * Mexican Mouse Opossum (Marmosa mexicana)
 * Linnaeus's Mouse Opossum (Marmosa murina)
 * Quechuan Mouse Opossum (Marmosa quichua)
 * Robinson's Mouse Opossum (Marmosa robinsoni)
 * Red Mouse Opossum (Marmosa rubra)
 * Tyleria Mouse Opossum (Marmosa tyleriana)
 * Guajira Mouse Opossum (Marmosa xerophila)
 * Genus Marmosops
 * Bishop's Slender Opossum (Marmosops bishopi)
 * Narrow-headed Slender Opossum (Marmosops cracens)
 * Marmosops creightoni
 * Dusky Slender Opossum (Marmosops fuscatus)
 * Handley's Slender Opossum (Marmosops handleyi)
 * Tschudi's Slender Opossum (Marmosops impavidus)
 * Gray Slender Opossum (Marmosops incanus)
 * Panama Slender Opossum (Marmosops invictus)
 * Junin Slender Opossum (Marmosops juninensis)
 * Neblina Slender Opossum (Marmosops neblina)
 * White-bellied Slender Opossum (Marmosops noctivagus)
 * Dorothys' Slender Opossum (Marmosops ocellatus)
 * Delicate Slender Opossum (Marmosops parvidens)
 * Brazilian Slender Opossum (Marmosops paulensis)
 * Pinheiro's Slender Opossum (Marmosops pinheiroi)
 * Genus Metachirus
 * Brown Four-eyed Opossum (Metachirus myosuros)
 * Genus Micoureus
 * Alston's Mouse Opossum (Micoureus alstoni)
 * White-bellied Woolly Mouse Opossum (Micoureus constantiae)
 * Woolly Mouse Opossum (Micoureus demerarae)
 * Tate's Woolly Mouse Opossum (Micoureus paraguayanus)
 * Little Woolly Mouse Opossum (Micoureus phaeus)
 * Bare-tailed Woolly Mouse Opossum (Micoureus regina)
 * Genus Monodelphis
 * Sepia Short-tailed Opossum (Monodelphis adusta)
 * Northern three-striped Opossum (Monodelphis americana)
 * Northern Red-sided Opossum (Monodelphis brevicaudata)
 * Yellow-sided Opossum (Monodelphis dimidiata)
 * Gray Short-tailed Opossum (Monodelphis domestica)
 * Emilia's Short-tailed Opossum (Monodelphis emiliae)
 * Amazonian Red-sided Opossum (Monodelphis glirina)
 * Ihering's Three-striped Opossum (Monodelphis iheringi)
 * Pygmy Short-tailed Opossum (Monodelphis kunsi)
 * Marajó Short-tailed Opossum (Monodelphis maraxina)
 * Osgood's Short-tailed Opossum (Monodelphis osgoodi)
 * Hooded Red-sided Opossum (Monodelphis palliolata)
 * Monodelphis reigi
 * Peruvian Short-tailed Opossum (Monodelphis ronaldi)
 * Chestnut-striped Opossum (Monodelphis rubida)
 * Long-nosed Short-tailed Opossum (Monodelphis scalops)
 * Southern Red-sided Opossum (Monodelphis sorex)
 * Southern Three-striped Opossum (Monodelphis theresa)
 * Red Three-striped Opossum (Monodelphis umbristriata)
 * One-striped Opossum (Monodelphis unistriata)
 * Genus Philander
 * Anderson's Four-eyed Opossum (Philander andersoni)
 * Philander deltae
 * Southeastern Four-eyed Opossum (Philander frenatus)
 * McIlhenny's Four-eyed Opossum (Philander mcilhennyi)
 * Philander mondolfii
 * Gray Four-eyed Opossum (Philander opossum)
 * Genus Thylamys
 * Cinderella Fat-tailed Mouse Opossum (Thylamys cinderella)
 * Elegant Fat-tailed Mouse Opossum (Thylamys elegans)
 * Karimi's Fat-tailed Mouse Opossum (Thylamys karimii)
 * Paraguayan Fat-tailed Mouse Opossum (Thylamys macrurus)
 * White-bellied Fat-tailed Mouse Opossum (Thylamys pallidior)
 * Common Fat-tailed Mouse Opossum (Thylamys pusillus)
 * Argentine Fat-tailed Mouse Opossum (Thylamys sponsorius)
 * Tate's Fat-tailed Mouse Opossum (Thylamys tatei)
 * Dwarf Fat-tailed Mouse Opossum (Thylamys velutinus)
 * Buff-bellied Fat-tailed Mouse Opossum (Thylamys venustus)
 * Genus Tlacuatzin
 * Gray Mouse Opossum (Tlacuatzin canescens)