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Philander opossumgray four-eyed opossum

By Michael Waters

Geographic Range

Philander opossum has a range that extends from Northeastern Mexico to Southeatern Brazil. Within this range, P. opossom may be found from Brazil's Atlantic coast westward into Peru and Argentenia, as well as throughout Central America. (Nowak 1997, Fonseca 1991, Cerqueira 1993)

Habitat

Philander opossum is found mainly in tropical forested areas, however, they may be found in the southern portions of South America in which the habitat is more temperate. In general, P. opossum resides in areas that receive greater than 1000 mm of rain per year.

Due to its proficient swimming ability, P. opossum may be found on islands. (Fonseca 1991, Adler 1996)

Physical Description

The common name is derived from this opossum's grey coat and the single white spots which are located directly above each eye, providing it with an appearance of four eyes.

The body length is 250-350 mm, and the tail reaches to about the same length. Males may be slightly larger than females, although much overlap in size is present. Females have five to nine mammae contained within a pouch.

The coloration of the short, straight hair is gray dorsally and off-white to yellow ventrally. The tail is furred with the same gray coloration for 50-60 mm from the base. The tip of the tail is naked and becomes paler in color towards its end.

The ears are naked as well.

Philander opossum has a slender body and a large head. Its rostrum is fairly long and narrows at the tip. The tail tapers as well, and it is prehensile. The hind limbs are longer and more muscular than the forelimbs. (Vieira 1997, Nowak 1997, Julien-Laferriere 1990)

  • Range mass
    220 to 680 g
    7.75 to 23.96 oz
  • Average basal metabolic rate
    1.886 W
    AnAge

Reproduction

Most populations of this species reproduce seasonally. During the rainy seasons, fruit is plentiful and more young may be cared for, while during the dry seasons, fruit is rare and few young are born. However, Philander opossum does reproduce throughout the year, but at lower levels during the months of June to August. Reproduction only ceases entirely when the mother's nutritional requirements are not met.

Although reproduction occurs year round, success is low. Death of young within the mother's pouch is common, especially during the dry months.

The young nurse in the mother's pouch, as that is where the nipples are located. Lactation lasts approximately 90 days, with much growth occurring after the weaning period. Following weaning, young P. opossum increase their body mass by a factor of ten.

Litter sizes vary from 1 to 7 young with the average litter containing 4 or 5 young. Larger females, those over 445 grams, tend to have larger litters (about 5 per birth), while smaller females, those under 445 grams, have fewer young per birth (about 3.8).

Females become sexually mature at about 6 to 8 months. At this time they weigh over 200 grams. Life expectancy is one to two years. (Julien-Laferriere 1990, Fleck 1995, D'Andrea 1994, Nowak 1997, Adler 1996)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
    5
    AnAge
  • Average birth mass
    0.2 g
    0.01 oz
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    450 days
    AnAge

Lifespan / Longevity

Behavior

Philander opossum can be found in dense populations that exhibit low mobility. While its range may extend as much as 300 meters, over fifty percent of the movements of this species occur within 30 meters.

Nests may be located on the ground or in burrows, but the majority of nests are built in the lower branches of trees, 8 to 10 meters from the ground. They are globular in nature and have a diameter of approximately 30 cm. While they usually nest in trees, much of the activity of these opossums is terrestrial. Philander opossum uses its more pronounced hind limbs for scampering and jumping along the forest floor. After being released from capture, P. opossum usually uses a terrestrial escape route rather than climbing trees. It is proficient at climbing and swimming.

Philander opossum is thought to be nocturnal; however, some researchers have witnessed an equal amount of activity in the day. When provoked, P. opossum gives a loud cry or hiss, and it is capable of savagely fighting. (Fleck 1995, Julien-Laferriere 1990, Vieira 1997, Cerqueira 1993), Nowak 1997, Adler 1996), Gentile 1995)

Communication and Perception

Food Habits

Philander opossum is omnivorous. About half of its diet consists of small animals such as insects, earthworms, birds, lizards, eggs, frogs, and small mammals. The remainder of the diet includes leaves, seeds, and fruits such as papayas and bananas. (Fleck 1995, Julien-Laferriere 1990, Nowak 1997, Fonseca 1991)

Economic Importance for Humans

Economic Importance for Humans: Positive

Philander opossum helps control the populations of insects and other small vertebrates. (Fonseca SD)

Economic Importance for Humans: Negative

Philander opossum has been known to feed upon corn fields and fruit crops, damaging farmers fields. (Nowak 1997)

Conservation Status

Currently Philander opossum is not thought to be threatend.

Contributors

Michael Waters (author), University of Michigan-Ann Arbor, Phil Myers (editor), 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

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

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.

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.

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.

scrub forest

scrub forests develop in areas that experience dry seasons.

sexual

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

tactile

uses touch to communicate

References

Adler, G., J. Saemon. 1996. Distribution of Four-eyed Opossum, Philander opossum on Small Islands in Panama. Mammalia, 60(1): 91-99.

Cerqueira, R. 1993. A Five-year Population Study of an Assemblance of Small Mammals in Southeastern Brazil. Mammalia, 57(4): 507-517.

D'Andrea, P., R. Cerqueira, E. Hingst. 1994. Age Estimation of the Gray Four-eyed Opossum, Philander opossum. Mammalia, 58(2): 283-291.

Fleck, D., J. Harder. 1995. Jounal of Mammalogy, 76(3): 809-818.

Fonseca, S., R. Cerqueira. 1991. Water and Salt Balance in a South American Marsupial, the Gray Four-eyed Opossum (Philander opossum). Mammalia, 55(3): 421-432.

Gentile, R., R. Cerqueira. 1995. Movement Patterns of Five Species of Small Mammals in a Brazilian Restinga.. Journal of Tropical Ecology, 11: 671-677.

Julien-Laferriere, D., M. Atramentowicz. 1990. Feeding and Reproduction of Three Didelphid Marsupials in Two Neotropical Forests (French Guiana). Biotropica, 22(4): 404-415.

Nowak, R. 1997. "Walker's Mammals of the World" (On-line). Accessed December 8, 1999 at http://www.press.jhu.edu/books/walkers_mammals_of_the_w.../.

Vieira, M. 1997. Body Size and Form in Two Neotropical Marsupials. Mammalia, 61(2): 245-254.

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