Virginia Opossum
Encyclopedia
The Virginia opossum commonly known as the North American opossum or tlacuache in Mexico, is the only marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...

 found in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 north of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. A solitary and nocturnal animal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

 about the size of a domestic cat, and thus the largest opossum, it is a successful opportunist. It is familiar to many North Americans as it is often seen near towns, rummaging through garbage cans, or lying by the road, a victim of traffic
Roadkill
Roadkill is an animal or animals that have been struck and killed by motor vehicles. In the United States of America, removal and disposal of animals struck by motor vehicles is usually the responsibility of the state's state trooper association or department of transportation.-History:During the...

.

Name

The Virginia opossum is the original animal named "opossum". The word comes from Algonquian
Algonquian languages
The Algonquian languages also Algonkian) are a subfamily of Native American languages which includes most of the languages in the Algic language family. The name of the Algonquian language family is distinguished from the orthographically similar Algonquin dialect of the Ojibwe language, which is a...

 'wapathemwa' meaning "white animal", not from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 or Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

, so the plural is opossums. Colloquially, the Virginia opossum is frequently called simply possum. The name is applied more generally to any of the other marsupials of the Didelphimorphia
Didelphimorphia
Opossums make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. They are also commonly called possums, though that term technically refers to Australian fauna of the suborder Phalangeriformes. The Virginia opossum was the first animal to be...

 and Paucituberculata orders, which includes a number of opossum species in South America.

The possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...

s of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, whose name is derived from a similarity to the Virginia opossum, are also marsupials, but of the order Diprotodontia
Diprotodontia
Diprotodontia is a large order of about 120 marsupial mammals including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the rhinoceros-sized Diprotodon, and Thylacoleo, the so-called "marsupial lion"....

.

Range

The Virginia opossum is found throughout Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and North America east of the Rockies from Costa Rica
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....

 to southern Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

; it seems to be still expanding its range northward and has been found farther north than Toronto
Toronto
Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...

. In recent years their range has expanded west and north all the way into northern Minnesota. Its ancestors evolved in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, but invaded North America in the Great American Interchange
Great American Interchange
The Great American Interchange was an important paleozoogeographic event in which land and freshwater fauna migrated from North America via Central America to South America and vice versa, as the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents...

, which was enabled by the formation of the Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...

 about 3 million years ago.

Originally native to the eastern United States, it was intentionally introduced into the West during the Great Depression
Great Depression
The Great Depression was a severe worldwide economic depression in the decade preceding World War II. The timing of the Great Depression varied across nations, but in most countries it started in about 1929 and lasted until the late 1930s or early 1940s...

, probably as a source of food, and now occupies much of the Pacific coast. Its range has been expanding steadily northwards into Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

.

Description

Virginia opossums can vary considerably in size, with larger specimens found to the north of the opossum's range and smaller specimens in the tropics. They measure 13–37 inch
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...

es (35–94 cm
Centimetre
A centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the SI base unit of length. Centi is the SI prefix for a factor of . Hence a centimetre can be written as or — meaning or respectively...

) long from their snout to the base of the tail, with the tail adding another 8.5–19 inch
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...

es (21.6–47 cm
Centimetre
A centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the SI base unit of length. Centi is the SI prefix for a factor of . Hence a centimetre can be written as or — meaning or respectively...

). Weight for males ranges from 1.7 to 14 pounds (0.8–6.4 kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...

) and for females from 11 ounces to 8.2 pounds (0.3–3.7 kg
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...

). Their coats are a dull grayish brown, other than on their faces, which are white. Opossums have long, hairless, prehensile tails, which can be used to grab branches and carry small objects. They also have hairless ears and a long, flat nose. Opossums have 50 teeth
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...

, the most out of any North American mammal, and opposable, clawless thumbs on their rear limbs.

Opossums have thirteen nipple
Nipple
In its most general form, a nipple is a structure from which a fluid emanates. More specifically, it is the projection on the breasts or udder of a mammal by which breast milk is delivered to a mother's young. In this sense, it is often called a teat, especially when referring to non-humans, and...

s, arranged in a circle of twelve with one in the middle.

Tracks

Virginia opossum tracks generally show five finger-like toes in both the fore and hind prints. The hind tracks are unusual and distinctive due to the opossum's opposable thumb
Thumb
The thumb is the first digit of the hand. When a person is standing in the medical anatomical position , the thumb is the lateral-most digit...

, which generally prints at an angle of 90 degrees or greater to the other fingers (sometimes near 180 degrees). Individual adult tracks generally measure 1⅞ inches long by 2 inches wide (4.8 × 5.1 cm) for the fore prints and 2½ inches long by 2¼ inches wide (6.4 × 5.7 cm) for the hind prints. Opossums have claws on all fingers fore and hind except on the two thumbs (in the photograph, claw marks show as small holes just beyond the tip of each finger); these generally show in the tracks but may not. In a soft medium, such as the mud in this photograph, the foot pads will clearly show (these are the deep, darker areas where the fingers and toes meet the rest of the hand or foot, which have been filled with plant debris by wind due to the advanced age of the tracks).

The tracks in the photograph were made while the opossum was walking with its typical pacing
Pacing
Pacing may refer to:* Pacing , a horse gait used in Standardbred horse races* Pacing, the even spreading out of athletes' strength in longer-distance track and field and swimming races, so that they don't burn themselves out...

 gait
Gait
Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency...

. The four aligned toes on the hind print show the approximate direction of travel.

In a pacing gait, the limbs on one side of the body are moved simultaneously, just prior to moving both limbs on the other side of the body. This is illustrated in the pacing diagram, which explains why the left-fore and right-hind tracks are generally found together (and vice versa). However if the opossum were not walking (but running, for example), the prints would fall in a different pattern. Other animals that generally employ a pacing gait are raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...

s, bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...

s, skunk
Skunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...

s, badger
Badger
Badgers are short-legged omnivores in the weasel family, Mustelidae. There are nine species of badger, in three subfamilies : Melinae , Mellivorinae , and Taxideinae...

s, woodchucks, porcupine
Porcupine
Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...

s and beaver
Beaver
The beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...

s.

When pacing, the opossum's stride generally measures from 7 to 10 inches, or approximately 18 to 25 cm (in the pacing diagram the stride is 8.5 inches, where one grid square is equal to one square inch). To determine the stride of a pacing gait, measure from the tip (just beyond the fingers or toes in the direction of travel, disregarding claw marks) of one set of fore/hind tracks to the tip of the next set. By taking careful stride and track-size measurements, one can usually determine what species of animal created a set of tracks, even when individual track details are vague or obscured.

Behavior

The Virginia opossum is noted for reacting to threats by feigning death. This is the genesis of the term "playing possum", which means pretending to be dead or injured with intent to deceive. In the case of the opossum, the reaction seems to be involuntary, and to be triggered by extreme fear. It should not be taken as an indication of docility, for under serious threat, an opossum will respond ferociously, hissing, screeching, and showing its teeth. But with enough stimulation, the opossum will enter a near coma, which can last up to four hours. It lies on its side, mouth and eyes open, tongue hanging out, emitting a green fluid from its anus whose putrid odor repels predators. Besides discouraging animals that eat live prey, playing possum also convinces some large animals that the opossum is no threat to their young.

Opossums are omnivorous
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...

 and eat a wide range of plants and animals such as fruits, insects, and other small animals. Persimmons
Diospyros virginiana
Diospyros virginiana, commonly called the American persimmon, common persimmon, Eastern persimmon, "'simmon" and "possumwood", is a persimmon species known by a variety of names including. It ranges from New England to Florida, and west to Texas, Louisiana, Oklahoma, and Kansas...

 are one of the opossum's favorite foods during the autumn. Opossums in captivity are known to engage in cannibalism, though this is probably uncommon in the wild. Placing an injured opossum in a confined space with its healthy counterparts is inadvisable.

The Virginia opossum does not hibernate, although it may remain sheltered during cold spells.

Perhaps surprisingly for such a widespread and successful species, the Virginia opossum has one of the lowest encephalization quotient
Brain to body mass ratio
Brain-to-body mass ratio, also known as the brain to body weight ratio, is the ratio of brain weight to body weight, which is hypothesised to be a rough estimate of the intelligence of an animal. A more complex measurement, encephalization quotient, takes into account allometric effects of widely...

s of any marsupial.

Life span

Opossums, like most marsupials, have unusually short life spans for their size and metabolic rate. The Virginia opossum has a maximal life span in the wild of only about two years. Even in captivity, opossums live only about four years. The rapid senescence
Senescence
Senescence or biological aging is the change in the biology of an organism as it ages after its maturity. Such changes range from those affecting its cells and their function to those affecting the whole organism...

 of opossums is thought to reflect the fact that they have few defenses against predators; given that they would have little prospect of living very long regardless, they are not under selective pressure to develop biochemical mechanisms to enable a long life span. In support of this hypothesis one population on Sapelo Island
Sapelo Island
Sapelo Island is a state-protected island located in McIntosh County, Georgia. The island is reachable only by airplane or boat, with the primary ferry coming from the Sapelo Island Visitors Center in McIntosh County, Georgia, a seven mile , twenty-minute trip.Approximately 97 percent of the...

, five miles off the coast of Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

, which has been isolated for up to thousands of years without natural predators was found by Dr. Steven Austad to have evolved life spans up to 50% longer than those of mainland populations.

Historical references

An early description of the opossum comes from explorer John Smith
John Smith of Jamestown
Captain John Smith Admiral of New England was an English soldier, explorer, and author. He was knighted for his services to Sigismund Bathory, Prince of Transylvania and friend Mózes Székely...

, who wrote in Map of Virginia, with a Description of the Countrey, the Commodities, People, Government and Religion in 1608 that "An Opassom hath an head like a Swine, and a taile like a Rat, and is of the bignes of a Cat. Under her belly she hath a bagge, wherein she lodgeth, carrieth, and sucketh her young."
The opossum was more formally described in 1698 in a 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
William Cowper (anatomist)
William Cowper FRS was an English surgeon and anatomist, famous for his early description of what is now known as the Cowper's gland....

, Chirurgeon, and Fellow of the Royal Society, London, by Edward Tyson, M. D. Fellow of the College of Physicians and of the Royal Society. The letter suggests even earlier descriptions.

Relationship with humans

Like raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...

s, opossums can be found in urban environments, where they eat pet food, rotten fruit, and human garbage. Though sometimes mistakenly considered to be rats, opossums are not closely related to rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s. They rarely transmit diseases to humans, and are surprisingly resistant to rabies
Rabies
Rabies is a viral disease that causes acute encephalitis in warm-blooded animals. It is zoonotic , most commonly by a bite from an infected animal. For a human, rabies is almost invariably fatal if post-exposure prophylaxis is not administered prior to the onset of severe symptoms...

, mainly because they have lower body temperatures than most placental mammals. In addition, opossums limit the spread of Lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...

, as they successfully kill off most disease carrying ticks that feed on them.

The opossum was once a favorite game animal in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, in particular in the southern regions which have a large body of recipes and folklore relating to it. Their past wide consumption in regions where present is evidenced by recipes available online and in books such as older editions of The Joy of Cooking
The Joy of Cooking
Joy of Cooking, often known as "The Joy of Cooking" is one of the United States' most-published cookbooks, and has been in print continuously since 1936 and with more than 18 million copies sold. It was privately published in 1931 by Irma S. Rombauer, a homemaker in St. Louis, Missouri, who was...

. A traditional method of preparation is baking, sometimes in a pie or pastry, though at present "possum pie" most often refers to a sweet confection containing no meat of any kind.

Although it is found throughout the country, the Virginia opossum's appearance in folklore and popularity as a food item has tied it closely to the American Southeast
Southeastern United States
The Southeastern United States, colloquially referred to as the Southeast, is the eastern portion of the Southern United States. It is one of the most populous regions in the United States of America....

. In animation, it is often used to depict uncivilized characters or "hillbillies
Hillbilly
Hillbilly is a term referring to certain people who dwell in rural, mountainous areas of the United States, primarily Appalachia but also the Ozarks. Owing to its strongly stereotypical connotations, the term is frequently considered derogatory, and so is usually offensive to those Americans of...

". The main character in Walt Kelly
Walt Kelly
Walter Crawford Kelly, Jr. , or Walt Kelly, was an American animator and cartoonist, best known for the comic strip, Pogo. He began his animation career in 1936 at Walt Disney Studios, contributing to Pinocchio and Fantasia. Kelly resigned in 1941 at the age of 28 to work at Post-Hall Syndicate,...

's long running comic strip Pogo was an opossum. In an attempt to create another icon like the teddy bear
Teddy bear
The teddy bear is a stuffed toy bear. They are usually stuffed with soft, white cotton and have smooth and soft fur. It is an enduring form of a stuffed animal in many countries, often serving the purpose of entertaining children. In recent times, some teddy bears have become collector's items...

, U.S. President William Howard Taft
William Howard Taft
William Howard Taft was the 27th President of the United States and later the tenth Chief Justice of the United States...

 was tied to the character Billy Possum. The character did not do well, as public perception of the opossum led to its downfall. In December 2010, a cross-eyed Virginia opossum in Germany's Leipzig Zoo named Heidi
Heidi (opossum)
Heidi was a Virginia Opossum housed at Germany's Leipzig Zoo. In December 2010, the two-and-a-half year old, cross-eyed animal made international headlines shortly after a photograph was published by Bild...

 became an international celebrity. She appeared on a TV talk show to predict the 2011 Oscar winners, similar to the World Cup predictions made previously by Paul the Octopus
Paul the Octopus
Paul the Octopus was a common octopus from Weymouth, England. Paul lived in a tank at a commercial attraction, the Sea Life Centre in Oberhausen, Germany and became internationally famous after his feeding behaviour was used to correctly predict the winner of each of the Germany national football...

, also in Germany.

External links

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