The gray four-eyed opossum (''Philander opossum'') is an

opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

from

Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

and South America, ranging from southern

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

and southwestern Brazil, at altitudes from sea level to 1600 m, but generally below . Its habitats include primary, secondary and disturbed forest. It is one of many opossum species in the order Didelphimorphia and the family Didelphidae.

Description

It has a sharply defined white spot above each eye, hence the common name. Its

prehensile Prehensility is the quality of an appendage or organ that has adapted for grasping or holding. The word is derived from the Latin term ''prehendere'', meaning "to grasp". The ability to grasp is likely derived from a number of different origi ...

tail is bicolored, with a pale distal part and a longer proximal darker gray part, and is naked at the end. Its

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

fur is gray, while its

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

fur, throat, and cheeks are cream-colored. Adults have ears that are black except at the base. Wild specimens weigh , while captive specimens can weigh up to . Body length ranges from with a tail in a similar size range, .

Behavior

The species is

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

solitary Solitary is the state of being alone or in solitude. The term may refer to: * shortened form of solitary confinement * Solitary animal, an animal that does not live with others in its species * Solitary but social, a type of social organization in ...

and partly

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...

. It is usually found in moist areas, often near streams, although it wanders in many different vegetation types. It is a good swimmer. Gray four-eyed opossums do not have a well defined territory, and home range stability depends on the availability of adequate resources. They are

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

, feeding on small animals and vegetation, such as leaves, seeds, and fruits. The gray four-eyed opossum does not "play dead" like the North American

Virginia opossum The Virginia opossum (''Didelphis virginiana''), also known as the North American opossum, is the only opossum living north of Mexico, its range extending south into Central America. It is the northernmost marsupial in the world. In the United S ...

. Instead it is aggressive and fights with potential predators. Some displays of aggression include opening the mouth wide and hissing loudly. It is known to be "the fiercest fighter of the opossums". The gray four-eyed opossum is a nocturnal animal but can be active during the day. Although it is terrestrial, it is very good at climbing and swimming. It has agile and swift movements, and seems more alert than other didelphids. Gray four-eyed opossums build nests out of dry leaves in hollow trees, tree forks, fallen logs and in ground burrows. They roll up into a ball while sleeping and although their eyes are actually closed, the white patches of fur above their eyes gives them the appearance of an awake animal.

Reproduction

Little is known about gray four-eyed opossums mating habits but they are in the family Didelphidae and so most likely to be

polygynous Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any ...

. This means males compete with other males. There are no courtship displays or pair bonds formed in didelphids. Reproduction is typically seasonal, with more young being born during the rainy season when there is an abundance of fruit. During the dry season, fewer babies are born due to the lack of available fruit. Litter sizes averaging between four and five young, with each female producing between two and four litters per year. Many young die while nursing in the mother's pouch. This death rate is especially high during the dry season. A major factor that determines survival of young is the mother's age; there are many deaths when the mother is less than 11 months. The average gestation period for the gray four-eyed opossum is 13 to 14 days, and each newborn weighs about . They nurse in their mother's pouch until they are 68 to 75 days old. Once weaned, they stay in their mother's nest for a further 8 to 15 days before their mother becomes aggressive and expels them.

Diet

The gray four-eyed opossum has an omnivorous diet containing fruits, nectar, insects, small mammals (such as mice), birds, reptiles, amphibians, crustaceans, snails, and earthworms. Its diet varies depending on the season. With such a varied diet, the gray four-eyed opossum will both encounter and eat venomous snakes. While the bites of these snakes may be harmful to most animals, the gray four-eyed opossum is able to overcome the toxic effects due to its immunity to the toxins. The immunity was initially thought to come from an immune response leading to the production of antibodies, but in fact it comes from toxin-neutralizing proteins found in opossum serum. These proteins are produced by the opossum prior to any encounter with a venomous snake, thus this immunity is not learned but inherited.

References

{{Taxonbar, from=Q194671 Opossums Marsupials of North America Marsupials of Central America Marsupials of South America Mammals of Brazil Mammals of Colombia Mammals of Guyana Mammals of Mexico Mammals of Bolivia Mammals described in 1758 Taxa named by Carl Linnaeus