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Opossum

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Didelphimorphia[1]
Temporal range: Late Cretaceous - Recent
File:Opossum 04 13 2007.jpg
Virginia Opossum Didelphis virginiana
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Infraclass:
Marsupialia
Order:
Didelphimorphia

Gill, 1872
Family:
Didelphidae

Gray, 1821
Genera

Several; see text

Opossum fur is quite soft, and was once commonly used in the bathtub as a sponge[citation needed].

Didelphimorphia is the order of common opossums of the Western Hemisphere. Opossums probably diverged from the basic South American marsupials in the late Cretaceous or early Paleocene. A sister group is Paucituberculata (shrew opossums). They are commonly also called "possums," though that term is also applied to Australian fauna of the suborder Phalangeriformes. The Virginia Opossum is the original animal named "opossum". The word comes from Algonquian wapathemwa, not Greek or Latin, so the plural is opossums. Colloquially, the Virginia opossum is frequently called simply possum.

Didelphimorphs are small to medium-sized marsupials, about the size of a large house cat. They tend to be semi-arboreal omnivores, although there are many exceptions. Most members of this taxon have long snouts, a narrow braincase, and a prominent sagittal crest. The dental formula (one side of one jaw) includes five incisors (four on the lower jaw), one canine, three premolars and four tricuspid molars. By mammal standards, this is a very full jaw. The incisors are very small, the canines large.

Didelphimorphs have a plantigrade stance (feet flat on the ground) and the hind feet have an opposable digit with no claw. Like some primates, opossums have prehensile tails. The stomach is simple, with a small cecum. Opossum reproductive systems are extremely basic, with a reduced marsupium. This means that the young are born at a very early stage. The species are moderately sexually dimorphic with males usually being somewhat larger than females.

Didelphimorphs are opportunistic omnivores with a very broad range of diet. Their unspecialized biology, flexible diet and reproductive strategy make them successful colonizers and survivors in unsettled times. Originally native to the eastern United States, the Virginia Opossum was intentionally introduced into the west during the Great Depression, probably as a source of food. Its range has been expanding steadily northwards, thanks in part to more plentiful, man-made sources of fresh water, increased shelter from urban encroachment, and milder winters. Its range has extended into Ontario, Canada, and it has been found farther north than Toronto.

Opossums are usually nomadic, staying in one area as long as food and water are easily available. Though they will temporarily occupy abandoned burrows, they do not dig or put much effort into building their own. They favor dark, secure areas, below ground or above.

When threatened or harmed, they will "play possum", mimicking the appearance and smell of a sick or dead animal. The lips are drawn back, teeth are bared, saliva foams around the mouth, and a foul-smelling fluid is secreted from the anal glands. The physiological response is involuntary, rather than a conscious act. Their stiff, curled form can be prodded, turned over, and even carried away. Many injured opossums have been killed by well-meaning people who find a catatonic animal and assume the worst. The best thing to do upon finding an injured or apparently dead opossum is to leave it in a quiet place with a clear exit path. In minutes or hours, the animal will regain consciousness and escape quietly on its own.

Adult opossums do not hang from trees by their tails, though babies may dangle temporarily. Their prehensile tails are not strong enough to support a mature adult's weight, though they often serve as a brace and a fifth limb when climbing. There are also confirmed accounts of the tail being used as a grip to carry bunches of leaves or bedding materials to the nest. A mother will sometimes carry her young upon her back, where they will cling tightly even when she is running across the ground or climbing.

Opossums have a remarkably robust immune system, and show partial or total immunity to the venom of rattlesnakes, cottonmouths, and other pit vipers.[2][3] Thanks to their lower blood temperature, rabies is almost unknown in opossums.[4]

The opossum lifespan is unusually short for a mammal of its size, usually only 2 to 4 years. Senescence is rapid.[5]

The opossum was described as early as 1565 in the published letter entitled "Carigueya, Seu Marsupiale Americanum Masculum. Or, The Anatomy of a Male Opossum: In a Letter to Dr Edward Tyson, from Mr William Cowper, Chirurgeon, and Fellow of the Royal Society, London. To Which are Premised Some Further Observations on the Opossum; And a New Division of Terrestrial Brute Animals, Particularly of Those That Have Their Feet Formed Like Hands. Where an Account is Given of Some Animals Not Yet Described", by Edward Tyson, M. D. Fellow of the College of Physicians and of the Royal Society. The letter suggests even earlier descriptions.[6]

Diagestion

The opossum was a favorite game animal in the United States, and in particular the southern regions which have a large body of recipes and folklore relating to the opossum. Opossum was once widely consumed in the United States, where available, as evidenced by recipes in older editions of The Joy of Cooking. In Dominica and Trinidad opossum or "manicou" is popular and can only be hunted during certain times of the ear due to over-hunting; the meat is traditionally prepared by smoking then stewing. The meat is light and fine grained and the musk glands must be removed as part of preparation. The meat can be used in place of rabbit and chicken in recipes. The cousin of the opossum, the possum, found in Australia and New Zealand is consumed in a similar manner. (Davidson, 1999)

Historically, hunters in the Caribbean would place a barrel with fresh or rotten fruit to attract opossums who would feed on the fruit or insects. Cubans growing up in the mid-twentieth century tell of brushing the maggots out of the mouths of "manicou" caught in this manner to prepare them for consumption. It is said also that the gaminess of the meat causes Flatulence gas.

In Mexico, opossums are known as "tlacuache". Their tails are eaten as a folk remedy to improve fertility (most likely because they have many babies that they store in their pouch).

Opossum oil (Possum grease) is high in essential fatty acids and has been used as a chest rub and a carrier for arthritis remedies given as topical salves.

Classification

References

  1. ^ a b Gardner, A. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 3–18. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ^ http://www.wildliferescueleague.org/report/opossum.html
  3. ^ http://www.scielo.br/scielo.php?pid=S0104-79301999000100005&script=sci_arttext
  4. ^ http://www.opossumsocietyus.org/frequently_asked_questions.htm#Do%20opossums%20carry%20rabies?
  5. ^ http://www.opossum.org/facts.htm
  6. ^ http://links.jstor.org/sici?sici=0022-2372%28193208%2913%3A3%3C241%3ATPCAPM%3E2.0.CO%3B2-0
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