The numbat (; binomen: Myrmecobius fasciatus), also known as the noombat or walpurti, is an insectivorous marsupial. It is diurnal and its diet consists almost exclusively of termites. The species was once widespread across southern Australia, but is now restricted to several small colonies in Western Australia. It is therefore considered an endangered species and protected by conservation programs. Numbats were recently re-introduced to fenced reserves in South Australia and New South Wales. The numbat is the faunal emblem of Western Australia.
Taxonomy The numbat genus Myrmecobius is the sole member of the family Myrmecobiidae, one of four families that make up the order Dasyuromorphia, the Australian marsupial carnivores. The species is not closely related to other extant marsupials; the current arrangement in the order Dasyuromorphia places its monotypic family with the diverse and carnivorous species of Dasyuridae. Genetic studies have shown that the ancestors of the numbat diverged from other marsupials between 32 and 42 million years ago, during the late Eocene. Two subspecies have been described, but one of these—the rusty coloured Myrmecobius fasciatus rufus Finlayson, 1933,—has been extinct since at least the 1960s, and only the nominate subspecies (M. fasciatus fasciatus) is extant. The population described by Finlayson occurred in the arid central regions of South Australia, and he thought they had once extended to the coast. The separation into subspecies was not recognised in the national census of Australian mammals, following W. D. L. Ride and others. As its name implies, M. fasciatus rufus had a more reddish coat than the surviving population. Only a very small number of fossil specimens are known, the oldest dating back to the Pleistocene, and no other species from the same family have been identified. The following is a phylogenetic tree based on mitochondrial genome sequences:
Placement of the family within the order of dasyuromorphs may be summarised as
Order Dasyuromorphia Family Thylacinidae Family Dasyuridae (72 species in 20 genera) Family Myrmecobiidae Genus Myrmecobius Species Myrmecobius fasciatus Family †Malleodectidae The common names are adopted from the extant names at the time of English colonisation, numbat, from the Nyungar language of southwest Australia, and walpurti, the name in the Pitjantjatjara dialect. The orthography and pronunciation of the Nyungar name is regularised, following a survey of published sources and contemporary consultation that resulted in the name noombat', pronounced noom'bat. Other names include banded anteater and marsupial anteater.
Description
The numbat is a small, distinctively-striped animal between 35 and 45 centimetres (14 and 18 in) long, including the tail, with a finely pointed muzzle and a prominent, bushy tail about the same length as its body. They have five toes on the fore feet, and four on the hind feet. Colour varies considerably, from soft grey to reddish-brown, often with an area of brick red on the upper back, and always with a conspicuous black stripe running from the tip of the muzzle through the eye to the base of the small, round-tipped ear. Between four and eleven white stripes cross the animal's hindquarters, which gradually become fainter towards the midback. The underside is cream or light grey, while the tail is covered with long, grey hair flecked with white. Weight varies between 280 and 700 g (10 and 24+1⁄2 oz). Numbats also possess a sternal scent gland, which may be used for marking their territories.
Unlike most other small marsupials, the numbat is diurnal, largely because of the constraints of having a specialised diet without having the usual physical equipment for it; most ecosystems with a generous supply of termites have a fairly large creature with powerful forelimbs bearing heavy claws, such as anteaters, aardvarks, and pangolins. Like other mammals that eat termites or ants (myrmecophages), the numbat has a "degenerate" jaw with up to 50 tiny, nonfunctional teeth, and although it is able to chew, rarely does so because of the soft nature of its diet. Uniquely among terrestrial mammals, an additional cheek tooth is located between the premolars and molars; whether this represents a supernumerary molar tooth or a deciduous tooth retained into adult life is unclear. As a result, although not all individuals have the same dental formula, in general, it follows the unique pattern: 4.1.3.1.43.1.4.1.4 Akin to other myrmecophages, the numbat has a long and narrow tongue coated with sticky saliva produced by large submandibular glands. A further adaptation to the diet is the presence of numerous ridges along the soft palate, which apparently help to scrape termites off the tongue so they can be swallowed. The digestive system is relatively simple and lacks many of the adaptations found in other insectivorous animals, presumably because termites are easier to digest than ants, having a softer exoskeleton. Numbats are apparently able to gain a considerable amount of water from their diets, since their kidneys lack the usual specialisations for retaining water found in other animals living in their arid environment. Although the numbat finds termite mounds primarily using scent, it has the highest visual acuity of any marsupial, and, unusually for marsupials, has a high proportion of cone cells in the retina. These are both likely adaptations for its diurnal habits, and vision does appear to be the primary sense used to detect potential predators.
Distribution and habitat
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