fat-tailed dunnart
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The fat-tailed dunnart (''Sminthopsis crassicaudata'') is a species of mouse-like
marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...
of the Dasyuridae, the family that includes the little red kaluta, quolls, and the Tasmanian devil.


Description

It has an average body length of with a tail of . Its ear length is . One of the smallest carnivorous marsupials, it varies in weight between . The tail becomes fat a few millimeters from the proximal end and remains so right up to the tip. The dunnart has trichromat vision, similar to that of some other marsupials as well as
primates Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians ( monkeys and apes). Primates arose 74–63  ...
, but unlike most mammals, which have dichromat vision.


Distribution and habitat

The range of ''S. crassicaudata'' in Australia is in diverse habitats except for the Kimberley region of
Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
and the northern
Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...
like
Arnhem Land Arnhem Land is a historical region of the Northern Territory of Australia. It is located in the north-eastern corner of the territory and is around from the territorial capital, Darwin, Northern Territory, Darwin. In 1623, Dutch East India Compa ...
and Kakadu National Park, but avoids the Wannon and Mallee scrub habitats in Victoria. In the northeast of Victoria, the species can also be found in
grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...
y
woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...
s and samphire shrublands. The subspecies ''S. c. crassicaudata'' is found in the Epping Forest National Park in
Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...
. ''S. c. ferruginea'' is found around Lake Eyre in South Australia. ''S. c. centralis'' is found in Killalpannina (as Killalpanima, Lake Eyre East), near Etadunna,
South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...
. Fat tailed dunnarts can be found in most deserts in Australia, e.g. the
Simpson Desert The Simpson Desert is a large area of dry, red sandy plain and dunes in the Northern Territory, South Australia and Queensland in central Australia. It is the fourth-largest Deserts of Australia, Australian desert, with an area of . The Wangka ...
and Gibson Desert. The habitats in which the species can be found include sparse grasslands, open shrublands and farmlands where there is considerable bare land. The impact of unimproved farming has been positive for this species as the type of habitat created is suitable to this dunnart's requirements, but intensive agriculture is seen as a negative factor for the species.


Social organisation and breeding

This species breeds from July to February, with the young in the pouch from July to April (Morton 1978b). Gestation is for 13 days and the young remain in the pouch for 70 days with litter size on average 7.5 with a 33% infant mortality rate. They generally have two litters per year, with females not breeding for the first year. The average life span of the females is 18 months, and males 15 months.


Diet

The fat-tailed dunnart's diet includes insects such as beetles, spiders, small reptiles, and amphibians. It stores fat reserves in its carrot-shaped tail for times of food shortage.


Survival

The fat-tailed dunnart is often eaten by other carnivores, including invasive foxes and
cats The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...
, as well as other feral animals that share its environment. The dunnart can survive in extreme, semi-arid environments. This is due to various physiological and behavioral characteristics. First, this
marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...
is nocturnal and functions within a 24-hour
circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...
. During the nighttime it is protected from high temperatures that cause energy loss. While awake, it spends the majority of its time feeding. Every night it consumes approximately its own body weight of food. During periods of food shortage it decreases its duration of activity while also increasing its intensity of feeding. It uses specialized, sharp teeth to grind its prey into fine pieces. This increases its ability to obtain nutrients from its prey. It has a high rate of digestion and can use fat stored in its tail as an energy source. Another survival technique that it uses is daily torpor. It lowers its body temperature and metabolic rate, in order to reduce energy expenditure. Torpor is unaffected by alterations in photoperiod but is greatly affected by environmental conditions. Two conditions must occur in order for the fat-tailed dunnart to use daily torpor: low ambient temperatures and food shortage. There are seasonal variations in torpidity. They use it more often in the winter because food is scarce and it requires more energy to maintain a high constant body temperature. During torpor, the body temperature can drop as low as 14.6 °C. This species does not use torpor for extended periods of time, thus the heart rate is variable and does not reach a steady state, such as seen in long-term torpidators. This species is unique in that it can use torpor during development and reproduction. Even during
lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process naturally occurs with all sexually mature female mammals, although it may predate mammals. The process ...
a female is capable of entering daily torpor without affecting the offspring. Coupled with the daily torpor is a process called re-warming. The re-warming process demands a high amount of energy in order to raise the body temperature. After awaking from a torpid state, these marsupials actively seek out areas in which they can bask in the sun to aid in this process. Nesting is also used as a behavioral survival technique. During times of cold temperatures, the fat-tailed dunnart shares nests with rodent species such as the house mouse, (''
Mus musculus The house mouse (''Mus musculus'') is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus ''Mus (genu ...
''), to conserve heat. This is unusual because the fat-tailed dunnart preys upon these mice during less extreme conditions. Group nesting is observed only during times of non-breeding.


Genetic proxy for thylacine

In August 2022, it was announced that the
University of Melbourne The University of Melbourne (colloquially known as Melbourne University) is a public university, public research university located in Melbourne, Australia. Founded in 1853, it is Australia's second oldest university and the oldest in the state ...
will partner with Texas-based biotechnology company Colossal Biosciences to attempt to re-create the
thylacine The thylacine (; binomial name ''Thylacinus cynocephalus''), also commonly known as the Tasmanian tiger or Tasmanian wolf, was a carnivorous marsupial that was native to the Mainland Australia, Australian mainland and the islands of Tasmani ...
using the fat-tailed dunnart, one of its closest living relatives, and return it to
Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...
.


References

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External links


Fat-tailed dunnart





Australian Biological Resources Study


{{Taxonbar, from=Q194519 Dasyuromorphs Mammals of Western Australia Mammals of South Australia Mammals of the Northern Territory Mammals of New South Wales Mammals of Victoria (state) Marsupials of Australia Mammals described in 1844 Taxa named by John Gould