Monodelphis domesticagray short-tailed opossum

Ge­o­graphic Range

Mon­odel­phis do­mes­tica is found through­out the forests of Brazil, Bo­livia, Ar­gentina, and Paraguay. ("Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001; Kala­fut, 2005; Wil­son and Reeder, 1993)

Habi­tat

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. ("Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001; Eisen­berg and Red­ford, 1999; Wil­son and Reeder, 1993)

Phys­i­cal De­scrip­tion

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. (Eisen­berg and Red­ford, 1999; Kala­fut, 2005; Trupin and Fadem, 1982; Unger, 1982)

  • Sexual Dimorphism
  • male larger
  • Range mass
    90 to 155 g
    3.17 to 5.46 oz
  • Range length
    10 to 15 cm
    3.94 to 5.91 in
  • Average basal metabolic rate
    0.335 W
    AnAge

Re­pro­duc­tion

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. ("Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001; Trupin and Fadem, 1982)

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. (Eisen­berg and Red­ford, 1999; "Amer­i­can Opos­sums", 2001; Eisen­berg and Red­ford, 1999; Kala­fut, 2005)

  • 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
  • Average number of offspring
    9
    AnAge
  • 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

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. (Kala­fut, 2005; Trupin and Fadem, 1982)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifes­pan/Longevity

Just over six years seems the most agreed upon upper lifes­pan in cap­tiv­ity. In the wild, two years is the stan­dard lifes­pan. ("Amer­i­can Opos­sums", 2001; Kala­fut, 2005)

  • 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

Be­hav­ior

Gray short-tailed opos­sums are soli­tary an­i­mals that ex­hibit ag­gres­sive be­hav­ior to­wards con­specifics. Nowhere is this more ev­i­dent than in breed­ing, where one of the two an­i­mals of the breed­ing pair is often wounded in the pre­cop­u­la­tory ag­gres­sive dance. More is known about M. do­mes­tica in cap­tiv­ity than in the wild. Nest build­ing be­hav­ior has only been seen, for in­stance, in an­i­mals in cap­tiv­ity. This be­hav­ior is seems to be for ther­moreg­u­la­tion and, in the wild, may pro­tect an­i­mals from mid­day heat. ("Amer­i­can Opos­sums", 2001; Fadem and Cor­bett, 1997; Kala­fut, 2005; Unger, 1982)

  • Range territory size
    8000 (high) m^2

Home Range

Small South Amer­i­can opos­sums like M. do­mes­tica gen­er­ally have fairly small ter­ri­to­ries, on the order of two acres or less. ("Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001; Em­mons and Feer, 1990; Fadem and Cor­bett, 1997)

Com­mu­ni­ca­tion and Per­cep­tion

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. (Eisen­berg and Red­ford, 1999; Fadem and Cor­bett, 1997; Kala­fut, 2005; Trupin and Fadem, 1982)

Food Habits

Gray short-tailed opos­sums are om­niv­o­rous, eat­ing in­sects, fruits, and small an­i­mals, such as ro­dents. (Fadem and Cor­bett, 1997; Kala­fut, 2005; Trupin and Fadem, 1982; Wil­son and Reeder, 1993)

  • Animal Foods
  • mammals
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit

Pre­da­tion

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

Ecosys­tem Roles

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. (Prod, 1968)

Com­men­sal/Par­a­sitic Species

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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. (Fadem and Cor­bett, 1997; Kala­fut, 2005; Trupin and Fadem, 1982; Unger, 1982; Wil­son and Reeder, 1993)

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

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Mon­odel­phis do­mes­tica can in­vade human dwellings and be­come an an­noy­ance. ("Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001; "Amer­i­can Opos­sums", 1984; "Amer­i­can Opos­sums", 2001)

  • Negative Impacts
  • household pest

Con­ser­va­tion Sta­tus

Mon­odel­phis do­mes­tica is both com­mon in the wild and in the pet trade. (Eisen­berg and Red­ford, 1999; Em­mons and Feer, 1990; Kala­fut, 2005)

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

David Moore (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor, in­struc­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

induced ovulation

ovulation is stimulated by the act of copulation (does not occur spontaneously)

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

Ref­er­ences

An­drom­eda Ox­ford Ltd. 1984. Amer­i­can Opos­sums. Pp. 830-837 in D Mac­don­ald, ed. The En­cy­clo­pe­dia of Mam­mals, Vol. 1/1, 1 Edi­tion. New York, NY: Facts On File, Inc..

An­drom­eda Ox­ford Ltd. 2001. Amer­i­can Opos­sums. Pp. 808-814 in D Mac­don­ald, S Nor­ris, eds. The New En­cy­clo­pe­dia of Mam­mals, Vol. 1/1, 1 Edi­tion. Ox­ford, UK: Ox­ford Uni­ver­sity Press.

Bergallo, H., R. Cerqueira. 1994. Re­pro­duc­tion and growth of the opos­sum, Mon­odel­phis do­mes­tica (Mam­malia:Didel­phi­dae) in north­east­ern Brazil. Jour­nal of Zo­ol­ogy, 232/4: 551-563.

Eisen­berg, J., K. Red­ford. 1999. Mam­mals of the Neotrop­ics: The Cen­tral Neotrop­ics, Vol. 3. Chicago, IL: The Uni­ver­sity of Chicago Press.

Em­mons, L., F. Feer. 1990. Neotrop­i­cal Rain­for­est Mam­mals: A Field Guide. Chicago, IL: The Uni­ver­sity of Chicago Press.

Fadem, B., A. Cor­bett. 1997. Sex Dif­fer­ences and the De­vel­op­ment of So­cial Be­hav­ior in a Mar­su­pial, the Gray Short-Tailed Opos­sum (Mon­odel­phis Do­mes­tica). Phys­i­ol­ogy and Be­hav­iour, 61/6: 857-861.

Kala­fut, M. 2005. "Know Your STO" (On-line). Short-Tailed Opos­sums, Keep­ing and Car­ing for These Pets. Ac­cessed Feb­ru­ary 15, 2006 at http://​www.​knowyoursto.​com/​.

Prod, H. 1968. Phopalias-Dob­bini New Species of Par­a­sitic Trema­tode of Mon­odel­phis-Do­mes­tica-Do­mes­tica. Bul­letin du Mu­seum Na­tional d'His­toire Na­turelle, 40/2: 393-395.

Stonerook, M., J. Harder. 1992. Sex­ual Mat­u­ra­tion if Fe­male Gray Short-Tailed Opos­sums Mon­odel­phis-Do­mes­tica is De­pen­dent Upon Male Stim­uli. Bi­ol­ogy of Re­pro­duc­tion, 46/2: 290-294.

Trupin, G., B. Fadem. 1982. Sex­ual Be­hav­ior of the Gray Short-Tailed Opos­sum (Mon­odel­phis Do­mes­tica). Jour­nal of Mam­mal­ogy, 63/3: 409-414.

Unger, K. 1982. Nest-Build­ing Be­hav­ior of the Brazil­ian Bare-Tailed Opos­sum, Mon­odel­phis Do­mes­tica. Jour­nal of Mam­mal­ogy, 63/1: 160-162.

Wil­son, D., D. Reeder. 1993. Mam­mal species of the world: a tax­o­nomic and ge­o­graphic ref­er­ence, 2nd ed.. Wash­ing­ton, D.C.: Smith­son­ian In­sti­tu­tion.