| Gray short-tailed opossum[1] | |
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Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Marsupialia |
| Order: | Didelphimorphia |
| Family: | Didelphidae |
| Genus: | Monodelphis |
| Species: | M. domestica |
| Binomial name | |
| Monodelphis domestica (Wagner, 1842) | |
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| Gray short-tailed opossum range | |
| Synonyms | |
Didelphys domestica | |
Thegray short-tailed opossum (Monodelphis domestica) is a small South American member of thefamilyDidelphidae. Unlike most othermarsupials, the gray short-tailed opossum does not have a truepouch. The scientific nameMonodelphis is derived fromGreek and means "single womb" (referring to the lack of a pouch) and theLatin worddomestica which means "domestic" (chosen because of the species' habit of entering human dwellings).[3] It was the first marsupial to have itsgenome sequenced. The gray short-tailed opossum is used as aresearch model in science,[4] and is also frequently found in theexotic pet trade. It is also known as theBrazilian opossum,rainforest opossum and in a research setting thelaboratory opossum.
Gray short-tailed opossums are relatively small animals, with a superficial resemblance tovoles. In the wild they have head-body length of 12 to 18 cm (4.7 to 7.1 in) and weigh 58 to 95 grams (2.0 to 3.4 oz); males are larger than females.[5] However, individuals kept in captivity are typically much larger, with males weighing up to 150 grams (5.3 oz).[6] As the common name implies, the tail is proportionately shorter than in some other opossum species, ranging from 5 to 9 centimetres (2.0 to 3.5 in).[5] Their tails are only semi-prehensile, unlike the fullyprehensile tail characteristic of theNorth American opossum.[3]
The fur is greyish brown over almost the entire body, although fading to a paler shade on the underparts, and with near-white fur on the feet. Only the base of the tail has fur, the remainder being almost entirely hairless.[5] The claws are well-developed and curved in shape, and the paws have small pads marked with finedermal ridges.[7] Unlike many other marsupials, females do not have a pouch. They typically possess thirteenteats,[8] which can be retracted into the body by muscles at their base.[5]
The gray short-tailed opossum is found generally south of theAmazon River, in southern, central, and westernBrazil. It is also found in easternBolivia, northernParaguay, and inFormosa Province in northernArgentina.[2] It inhabitsrainforest environments,scrubland, and agricultural land, and often enters man-made structures, such as houses.[5] There are no recognised subspecies.
Gray short-tailed opossums eatrodents, frogs,reptiles, andinvertebrates, as well as some fruit. They hunt primarily by scent, poking their snout into vegetation in search of prey or dead animals to scavenge. Once they find living prey, they pounce onto it, holding it down with their forefeet while delivering a killing strike, often to the base of the neck, with their sharp teeth. They can successfully take prey up to their own size.[5]
They arenocturnal, being most active in the first three hours after dusk. Although they may occasionally shelter in natural crevices in the rock, they normally spend the day in concealed nests constructed of leaves, bark, and other available materials. The nests of females are more complex and tightly woven than those of males. They are solitary, coming together only to mate, and with each individual occupying a home range of 1,200 to 1,800 m2 (13,000 to 19,000 sq ft), flagged withscent marks. The approach of another member of the species is commonly met with hissing and screeching, which may escalate to defensive strikes launched while the animal is standing on its hind legs.[5]
The opossums breed year round when the climate is suitable, being able to raise up to six litters of six to eleven young each during a good year. Females only come intooestrus when exposed to malepheromones, withovulation beinginduced only by physical contact with the male.[9] Gestation lasts fourteen days, after which the young attach to a teat, where they remain for the next two weeks. Like all marsupials, the young are born undeveloped; in this species they are just 1 centimetre (0.39 in) in length and weigh 0.1 grams (0.0035 oz) at birth.[10] The young grow hair at around three weeks, open their eyes about a week later,[5] and are weaned at eight weeks[11]
Gray short-tailed opossums are sexually mature at five to six months of age, and live for up to forty-nine months in captivity.[5]
The gray short-tailed opossum possesses several features that make it an idealresearch model, particularly in studies ofmarsupials, as well as theimmunological and developmental research onmammalian systems. It breeds relatively easily in laboratory settings, andneonates are exposed and can be readily accessed because, unlike other marsupial species, female opossums lack apouch: neonates simply cling to the teats. Opossums are born at a stage that is approximately equivalent to 13- to 15-day-old fetalrats or 40-day-old humanembryos. Like other marsupials, the inadequacies of the neonate's immune system function make it an ideal model for bothtransplant andcancer research, as well as general investigations intoimmune system development and its similarities to other eutherian mammals.[12][13]Itsgenome was sequenced and a working draft published in May 2007:[14] the decoding work, directed byMIT andHarvard, reveals the opossum to have between 18,000 and 20,000protein-coding genes. The full genome sequence and annotation can be found on theEnsembl Genome Browser.[15]
Authority control databases: National |
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