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Thylamys eleganselegant fat-tailed opossum

By Tom Giarla

Geographic Range

Thylamys elegans appears to be restricted to central Chile, but further surveys are needed to determine the limits of its distribution (Giarla et al., 2010). (Giarla, et al., 2010)

Habitat

Thylamys elegans primarily inhabits the Chilean Matorral, an ecoregion characterized by a Mediterranean climate and sclerophyllous vegetation. The Atacama desert lies to the north of the Matorral, and Thylamys elegans might inhabit parts of this habitat as well. (Giarla, et al., 2010; Palma, 1997)

  • Range elevation
    0 to 1000 m
    0.00 to 3280.84 ft

Physical Description

Like other members of its genus, Thylamys elegans is notable for its incrassate (fattened) tail. The size of the tail varies by season in accordance with food availability. This species is tricolored, with darker dorsal fur, paler lateral fur, and a cream-colored ventral region. Giarla et al. (2010) report body lengths of 90 to 127 mm, with tails 105 to 134 mm long. Although this species is a marsupial, females do not have a pouch (Palma, 1997). Bozinovic et al. (2005) report a basal metabolic rate of 1.07 mL oxygen per gram-hour-ºC (Bozinovic, et al., 2005; Giarla, et al., 2010; Palma, 1997)

  • Range length
    195 to 261 mm
    7.68 to 10.28 in
  • Average basal metabolic rate
    1.07 cm3.O2/g/hr

Reproduction

Little is known about the mating system in Thylamys elegans. Palma (1997) reports that two adults have never been found in the same nest, suggesting that this species does not form monogamous breeding pairs. (Palma, 1997)

Breeding season for Thylamys elegans occurs from September through March, with females having one or two litters per season. Up to 17 embryos have been reported, but survival is limited by the number of functional nipples on the female, which is typically 11 to 13 (Palma, 1997). (Palma, 1997)

  • Breeding interval
    Thylamys elegans has one or two litters per breeding season
  • Breeding season
    Breeding occurs from September to March.
  • Range number of offspring
    17 (high)
  • Average number of offspring
    12

Little is known about parental care in Thylamys elegans. Like other Thylamys species, females lack a pouch and exposed young cling to the nipples. (Giarla, et al., 2010)

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

Lifespan/Longevity

No published records of lifespan exist for this species.

Behavior

Little is known about the behavior of Thylamys elegans. This species is likely solitary, as most small, insectivorous mammals are. As is the case for other members of this genus, Thylamys elegans is nocturnal and experiences daily torpor. Individuals build nests out of hair and leaves in rocks, trees, and abandoned rodent burrows (Palma 1997). (Palma, 1997)

  • Range territory size
    800 to 1400 m^2

Home Range

In winter, the home range of Thylamys elegans was estimated to be approximately 1,400 square meters. In summer, this species' home range is smaller and estimated to be approximately 800 square meters. (Palma, 1997)

Communication and Perception

Because this species is small and nocturnal, communication between individuals is likely primarily olfactory in nature. Palma (1997) reports that the olfactory and visual regions of this species' brain are especially well developed. (Palma, 1997)

Food Habits

Like other Thylamys species, Thylamys elegans primarily consumes insects, although it occasionally eats small vertebrates, leaves, fruit, seeds, and carrion (Palma 1997). (Palma, 1997)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • reptiles
  • carrion
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

Like other small mammals, Thylamys elegans is likely well adapted to avoiding predators by being nocturnal and inconspicuous. (Palma, 1997)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Thylamys elegans acts as an important predator of many arthropod species and some small vertebrates. It is prey to several bird and medium-sized mammals, such as owls and foxes. It is likely host to many ecto- and endoparasites. More specific information about the ecosystem role of Thylamys elegans is not presently available. (Palma, 1997)

Economic Importance for Humans: Positive

This species likely has little direct impact on humans.

Economic Importance for Humans: Negative

This species likely has little direct impact on humans.

Conservation Status

Thylamys elegans is considered "least concern" by the IUCN.

Contributors

Tom Giarla (author), University of Minnesota, Sharon Jansa (editor), American Museum of Natural History, Robert Voss (editor), American Museum of Natural History, Tanya Dewey (editor), 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

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.

arboreal

Referring to an animal that lives in trees; tree-climbing.

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.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

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.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

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.

female parental care

parental care is carried out by females

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

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

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

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

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

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.

References

Bozinovic, F., G. Ruiz, A. Cortes, M. Rosenmann. 2005. Energetics, thermoregulation and torpor in the Chilean mouse-opossum Thylamys elegans (Didelphidae). Revista Chilena de Historia Natural, 78: 199-206.

Giarla, T., R. Voss, S. Jansa. 2010. Species Limits and Phylogenetic Relationships in the Didelphid Marsupial Genus Thylamys Based on Mitochondrial DNA Sequences and Morphology. Bulletin of the American Museum of Natural History, 346: 1-67.

Palma, R. 1997. Thylamys elegans. Mammalian Species, 572: 1-4.

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