Gray short-tailed opossums vocalize when threatened or approached by a possible mate. A series of chirps or barks is used to advertise threat level. Olfaction also plays an important role in the lives of gray short-tailed opossums; scent marking is used for territorial purposes and for assessment of reproductive condition of females.
Communication Channels: visual ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Monodelphis domestica is both common in the wild and in the pet trade.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Monodelphis domestica can invade human dwellings and become an annoyance.
Negative Impacts: household pest
Gray short-tailed opossums have become a popular species in the exotic pet trade. They are important in research because they are one of the few animals to get skin cancer at a rate similar to humans. Gray short-tailed opossums are at the top of the list for full genome sequencing. Dozens of research projects are currently being done with M. domestica.
Gray short-tailed opossums are often welcome visitors in human households, as they consume insects, scorpions, and other pests.
Positive Impacts: pet trade ; research and education
Gray short-tailed opossums are insectivores and negatively impact insect populations where they occur. No list of predators which feed upon M. domestica has been published; however, they are likely part of the diets of other mammalian carnivores, such as other didelphids, and large birds of prey. Monodelphis domestica also acts as a host for a variety of parasites, such as the echinostomatiform protozoan Rhopalias dobbini.
Commensal/Parasitic Species:
Gray short-tailed opossums are omnivorous, eating insects, fruits, and small animals, such as rodents.
Animal Foods: mammals; insects; terrestrial non-insect arthropods
Plant Foods: fruit
Primary Diet: omnivore
Monodelphis domestica is found throughout the forests of Brazil, Bolivia, Argentina, and Paraguay.
Biogeographic Regions: neotropical (Native )
Gray short-tailed opossums are found in tropical forests, scrublands, and grassy areas, on the ground or in low level vegetation. As with other short-tailed opossums (Monodelphis), gray short-tailed opossums may inhabit human dwellings, where they feed on small rodents and insects.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest
Other Habitat Features: suburban ; agricultural
Just over six years seems the most agreed upon upper lifespan in captivity. In the wild, two years is the standard lifespan.
Range lifespan
Status: wild: 3 to 6 years.
Average lifespan
Status: wild: 4 years.
Range lifespan
Status: captivity: 6 to 10 years.
Typical lifespan
Status: wild: 1 to 3 years.
Typical lifespan
Status: captivity: 2 to 6 years.
Monodelphis domestica is a member of the group of short-tailed opossums, Monodelphis, which are some of the smallest didelphids. Body length of adults ranges from 10 to 15 cm. Adult males weigh between 90 and 155 g, females are between 80 and 100 g. Most individuals have light grey fur, but fur color does vary, with some popluations having more reddish or whitish fur. Their tails are naked, rat-like, and semi-prehensile. Tail length varies but is usually about half the length of the of body.
Range mass: 90 to 155 g.
Range length: 10 to 15 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Average basal metabolic rate: 0.335 W.
Specific information on predators of M. domestica was not found. Harpy eagles (Harpia harpyja), other birds of prey, and other predatory mammals are likely predators. Gray short-tailed opossums are cryptically colored and secretive, thereby avoiding some predation.
Anti-predator Adaptations: cryptic
Mating behavior in M. domestica is strongly tied to olfaction. Males habitually mark their surroundings with a chemical mark produced by a sternal gland. This scent likely serves as an advertisement to local females and a warning to local males. When a male and a receptive female meet, a precopulatory dance of sniffing, chasing, biting, and licking ensues. At the completion of this dance, the male immobilizes the female's hind legs and begins copulation, which lasts from 4 to 7 minutes. The majority of matings take place with the animals laying on their right sides.
Mating System: polygynandrous (promiscuous)
Sexual maturity in M. domestica is reached by 18 to 20 weeks. Gestation lasts 14 to 15 days and females can have up to 5 litters per year. Typical litter size is from 7 to 9.
Breeding interval: On average gray short-tailed opossums breed 4 times per year.
Breeding season: In the wild, breeding occurs most often during the spring and summer months, when daylight hours are the longest.
Range number of offspring: 1 to 15.
Range gestation period: 14 to 15 days.
Range weaning age: 3 to 4 weeks.
Average weaning age: 3 weeks.
Range time to independence: 6 to 8 weeks.
Range age at sexual or reproductive maturity (female): 5 to 7 months.
Range age at sexual or reproductive maturity (male): 5 to 7 months.
Key Reproductive Features: seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; induced ovulation ; viviparous
Average birth mass: 0.1 g.
Average number of offspring: 9.
Immediately after birth, newborn M. domestica crawl to their mother's stomach and attach to a nipple. They remain attached this way for 3 to 4 weeks. After detachment the young climb on their mother and/or follow her around for another three months or more. Paternal care in M. domestica is nonexistent, moreover, in captivity when fathers are confronted with their offspring, they act aggressively towards them.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
The gray short-tailed opossum (Monodelphis domestica) is a small South American member of the family Didelphidae. Unlike most other marsupials, the gray short-tailed opossum does not have a true pouch. The scientific name Monodelphis is derived from Greek and means "single womb" (referring to the lack of a pouch) and the Latin word domestica which means "domestic" (chosen because of the species' habit of entering human dwellings).[3] It was the first marsupial to have its genome sequenced. The gray short-tailed opossum is used as a research model in science,[4] and is also frequently found in the exotic pet trade. It is also known as the Brazilian opossum, rainforest opossum and in a research setting the laboratory opossum.
Gray short-tailed opossums are relatively small animals, with a superficial resemblance to voles. 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 fully prehensile tail characteristic of the North 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 fine dermal ridges.[7] Unlike many other marsupials, females do not have a pouch. They typically possess thirteen teats,[8] which can be retracted into the body by muscles at their base.[5]
The gray short-tailed opossum is found generally south of the Amazon River, in southern, central, and western Brazil. It is also found in eastern Bolivia, northern Paraguay, and in Formosa Province in northern Argentina.[2] It inhabits rainforest environments, scrubland, and agricultural land, and often enters man-made structures, such as houses.[5] There are no recognised subspecies.
Gray short-tailed opossums eat rodents, frogs, reptiles, and invertebrates, 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 are nocturnal, 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 with scent 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 into oestrus when exposed to male pheromones, with ovulation being induced 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 ideal research model, particularly in studies of marsupials, as well as the immunological and developmental research on mammalian systems. It breeds relatively easily in laboratory settings, and neonates are exposed and can be readily accessed because, unlike other marsupial species, female opossums lack a pouch: neonates simply cling to the teats. Opossums are born at a stage that is approximately equivalent to 13- to 15-day-old fetal rats or 40-day-old human embryos. Like other marsupials, the inadequacies of the neonate's immune system function make it an ideal model for both transplant and cancer research, as well as general investigations into immune system development and its similarities to other eutherian mammals.[12][13] Its genome was sequenced and a working draft published in May 2007:[14] the decoding work, directed by MIT and Harvard, reveals the opossum to have between 18,000 and 20,000 protein-coding genes. The full genome sequence and annotation can be found on the Ensembl Genome Browser.[15]
The gray short-tailed opossum (Monodelphis domestica) is a small South American member of the family Didelphidae. Unlike most other marsupials, the gray short-tailed opossum does not have a true pouch. The scientific name Monodelphis is derived from Greek and means "single womb" (referring to the lack of a pouch) and the Latin word domestica which means "domestic" (chosen because of the species' habit of entering human dwellings). It was the first marsupial to have its genome sequenced. The gray short-tailed opossum is used as a research model in science, and is also frequently found in the exotic pet trade. It is also known as the Brazilian opossum, rainforest opossum and in a research setting the laboratory opossum.
