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Xeromys myoidesfalse water rat

By Maureen Suter

Geographic Range

The geographic range of Xeromys myoides is restricted to Australia. Though originally known only in Southeast Queensland and the Northern Territory, the false water-rat is currently found in the central and southern parts of Queensland, North Stradbroke Island off the coast of Southeast Queensland, the Northern territory, and on the nearby Melville Island (Wilson and Reeder, 1993; Nowak, 1999)

Habitat

The false water-rat is found mainly in coastal swamps with mangrove forest. It has also been recorded near freshwater lagoons, sedged lakes, and grassy and reed swamps. It appears to dependend on mangrove habitats for food aquisition (Nowak, 1999; Strahan, 1995).

Physical Description

False water-rats have markedly long, flattened heads with small eyes and short, rounded ears. These rats possess just two molars on each side of the upper and lower jaw. Their upper incisors are yellow or orange and the lower incisors are white.

The head and body length of the false water-rat is 115-27mm. The tail length is 85-100mm and the hind-foot length is 23-26mm. Body fur is generally dark gray, which gradually blends into the white underside. This coat is water-resistant. The hands, feet, and tail are covered with fine, white hairs, and the feet are not webbed. The tail of these rats is scaled.

Females have four teats (Nowak, 1999; Taylor, 1984).

  • Range mass
    40 to 60 g
    1.41 to 2.11 oz

Reproduction

Very little is known about the false water-rat's reproductive behavior. It is thought to be in breeding condition throughout the year. Litter size does not exceed 2 (Van Dyck, 1997; Taylor, 1984).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

The false water-rat is nocturnal, foraging by night and resting in it nest by day. Their nests are found at the base of mangrove trees, among their roots. They also nest in sedgeland. The nests, which resemble termite mounds, are composed of leaves and compact mud and are about 60 cm high. While there is typically a single opening to this mound, inside, a complex system of tunnels connects multliple chambers. The nests are usually inhabited by one male, several females, and multiple juveniles with a total of up to 8 residents. At night, when the tide recedes, these rats leave their nests to forage among the mangrove forests.

False water-rats have slightly overlapping home ranges that are estimated at about 0.8 ha for males and 0.6 ha for females (Nowak, 1999; Strahan,1995; Queensland Museum Explorer,1999).

Communication and Perception

Food Habits

The false water-rat's diet is very much dependent on its swampy habitat. They appear to feed on small crustaceans such as crabs, marine polyclads, marine pulmonates, shellfish, and worms. In captivity, the false water-rat will eat insects, fish, lizards, crabs that are larger than itself (Nowak, 1999; Van Dyck, 1997; Queensland Museum Explorer, 1999).

Economic Importance for Humans: Positive

The false water-rat has no positive economic importance for humans. But by playing a role in maintaining the ecological stability of the marine population it feeds on, it may indirectly effect local marine-related industries.

Economic Importance for Humans: Negative

The false water-rat does not appear to negatively effect humans or the economy.

Conservation Status

Since its initial description in 1889, only a very small number of specimens have been collected, mostly since 1970. It is evident that these rats are intimately connected to their mangrove habitat. Habitat distruction due to agriculture, livestock grazing, urbanization, and swamp drainage are considered major threats to the survival of this animal. In addition, off-shore pollution and land reclamation pose a threat to this rare species (Queensland Museum Explorer, 1999; Strahan, 1995; Nowak, 1999).

Other Comments

The water rat in the genus Hydromys is phyogenetically distantly related to the false water-rat, although the two are still considered sister genera (Wilson and Reeder, 1993).

Contributors

Maureen Suter (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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

coastal

the nearshore aquatic habitats near a coast, or shoreline.

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.

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.

sexual

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

tactile

uses touch to communicate

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.

References

1999. "Queensland Museum Explorer" (On-line). Accessed December 11, 1999 at http://www.qmuseum.qld.gov.au/.

Nowak, R. 1999. Walker's Mammals of the World 6th ed.. Baltimore: Johns Hopkins University Press.

Strahan, R. 1995. The Mammals of Australia. Chatswood, Australia: Reed Books.

Taylor, M. 1984. The Oxford Guide to Mammals of Australia. Melbourne, Australia: Oxford University Press.

Van Dyck, S. 1997. Xeromys myoides Thomas, 1889 (Rodentia: Muridae) in mangrove communities of North Stradbroke Island, Southeast Queensland. Memoirs of the Queensland Museum, 42(1): 337-366.

Wilson, D., D. Reeder. 1993. Mammal Species of the World: A taxonomic and geographic reference 2nd ed.. Washington: Smithsonian Institution Press.

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