Notoryctemorphia

Marsupial moles

(Notoryctidae)

Class Mammalia

Order Notoryctemorphia

Family Notoryctidae

Number of families 1

Thumbnail description
Long, flexible body like a flattened cylinder a with short tail and very short stout legs; front feet bear two large spade-like claws; fur is silky and pale blond, nose has flat, callused shield and there are no visible eyes or ears; females have two teats within a backward opening pouch

Size
3.5–7 in (9–18 cm); tail about 1 in (2.5 cm); weight 1.2–2.5 oz (35–70 g)

Number of genera, species
1 genus; 2 species

Habitat
Hot arid sandy desert

Conservation status
Endangered: 2 species

Distribution
Western and central Western Australia

Evolution and systematics

In terms of appearance and habits, the marsupial moles are about as different from most other marsupials as it is possible to be. In fact, they bear an uncanny resemblance to African golden moles (Eremitalpa spp.). These similarities are due entirely to the convergent evolution of adaptations to a similar "sand-swimming" lifestyle. The marsupial moles have no close relatives. There is no doubt these extraordinary animals are marsupials, but even DNA analysis has been so far unable to connect them to any other living marsupial group, and it is believed they belong to a lineage that diverged from other marsupials more than 50 million years ago. The evolutionary history of the marsupial moles was made a little clearer by the discovery in 1987 of a fossil form in Tertiary rocks of the world-famous Riversleigh system in Queensland. It is now thought the ancestor of Notoryctes may have been a similar kind of animal, which developed its burrowing habit in order to feed in the soft litter of decomposing leaves in an ancient tropical rainforest. What started as an adaptation for rummaging through the humus layer may have evolved into the sand-swimming technique employed by marsupial moles in later, drier habitats.

Marsupial moles spend most of their time beneath the sand in one of the world's least explored regions—the deserts of central and western Australia. As a result, they are difficult to study in the wild. They have also proved impossible to keep for long in captivity and, consequently, many aspects of their biology remain a mystery.

Physical characteristics

There is no mistaking a marsupial mole for any other Australian mammal. Both species have a body shaped like a flattened cylinder, with very short legs and a short, stiff tail. The body is covered in very fine, almost iridescent golden fur, which is often stained by the red desert soil. There are no visible eyes, just dark spots marking the place where vestigial lenses lie under the skin. The ears are mere holes in the side of the head, protected by dense fur. The only distinctive feature

of the face is a horny, hairless nose-shield, slightly bigger in the southern species, N. typhlops.

There are five toes on each foot. On the front feet, the first and second toes oppose the others, and the third and fourth are big with very large, spade-like claws, used for digging. The fifth front toe is small, as are the first and fifth toes of the hind feet. The tail is annulated (ringed), with a knobbly end. Females have a rearward opening pouch concealing two teats.

Distribution

The distribution of marsupial moles is difficult to map with precision, partly because of the paucity of sightings and also because most early records were not accurately mapped—locations were indicated to the nearest town or station, often 100 mi (161 km) or more away. However, it appears that the smaller species, the northern marsupial mole, N. caurinus, occurs from the vicinity of Eighty Mile Beach on the northwest corner of Western Australia, southeast toward the central desert. The larger species, N. typhlops, occurs as far south as the Nullabor Plain bordering the Great Australian Bight and east into southwestern Queensland. Where and to what extent the two species overlap is not known.

Habitat

Marsupial moles are sand-dwellers. They were originally given the generic name, Psammoryctes, meaning "sand digger," but this had to be changed when it was realized this name had already been given to a group of oligochaete worms. Notoryctes spp. live in sand dunes and flat plains, and especially in the flatlands created where seasonal rivers flood the desert. They appear to be especially active in damp sand—most surface sightings occur shortly after rain. Often these habitats are vegetated with sparse spinfex grass or mulga scrub. The moles typically dig between 4 and 8 in (9–18 cm) under the sand, but occasionally burrow as deep as 8 ft (2.5m). They are sensitive to cold, becoming chilled at temperatures less than 59°F (15°C), and readily succumb to hypothermia.

Behavior

What little is known about the lives of marsupial moles suggests they live alone and spend almost all their time underground, moving through the sand with a swimming action. They dig incredibly fast and are capable of shoving their way into the sand in seconds. They burrow faster than most potential predators can shift sand as they attempt to dig the moles out. Marsupial moles do not leave tunnels—the sand collapses behind them as they move. On the surface, marsupial

moles move with a sinuous gait, the body shimmying from side to side as the short legs on opposite corners move together in awkward shuffling steps, leaving a distinctive trail of wiggly lines in the sand.

Feeding ecology and diet

Stomach contents indicate that marsupial moles have a mostly insectivorous diet, comprising ants, termites, and the larvae of other insects. They also eat other invertebrates and small lizards, and occasional seeds and other plant material. Food is apparently dug out of the sand as the animal burrows.

Reproductive biology

Virtually nothing is known about breeding behavior of marsupial moles. Of the few females with young that have been found, none have more than two babies—one for each teat.

Conservation status

The IUCN lists both species of marsupial mole as Endangered. There is no hard evidence that the species' ranges have decreased, but there is anecdotal evidence for an over-decline in abundance. Normally, an animal about which so little is known would be listed as Data Deficient, but conservationists are taking no chances with these extraordinary marsupials, which are given full legal protection. The main concerns are changes in land use, in particular burning regimes, and introduced predators such as foxes, whose dropping have occasionally been found to contain marsupial mole remains.

Significance to humans

Marsupial moles have very little practical value to humans. Indigenous Australians may occasionally have used them as food, but these days more people regard these little-known animals as rare and precious. Sightings are rare enough to make the news, and specimens are being collected at the rate of one or two a year. The last specimen to be collected alive was found in the Punmu region of Western Australia in 1999. Sadly, the animal lived for only six weeks in captivity.

Species accounts

List of Species

Marsupial mole

Notoryctes typhlops

taxonomy

Notoryctes typhlops (Stirling, 1889), Indracowrie, Northern Territory, Australia.

other common names

English: Greater marsupial mole; French: Taupe marsupiale; German: Großer Beutelmull; Spanish: Topo marsupial.

physical characteristics

Head-body 3.5–7 in (9–18 cm); tail about 1 in (2.5 cm); weight 1.2–2.5 oz (35–70 g). Long, flattish body with short tail, very short, stout legs, and spade-like front feet; fur is silky and pale blond; no visible eyes or ears, nose has flat, callused shield; female has backward opening pouch with two teats.

distribution

Midwestern Australia, including central Western Australia, southern Northern Territories, and northwestern South Australia.

habitat

Sandy desert.

behavior

Lives alone; burrows in loose sand using swimming action, but creates no persistent burrow system, surfaces very occasionally.

feeding ecology and diet

Mostly insect larvae.

reproductive biology

Nothing is known.

conservation status

Endangered.

significance to humans

None known.

Northern marsupial mole

Notoryctes caurinus

taxonomy

Notoryctes caurinus Thomas, 1920, Ninety Mile Beach, Wallal, Western Australia, Australia. Formerly part of N. typhlops, but separated in 1988.

other common names

English: Lesser marsupial mole; French: Taupe marsupiale; German: Kleiner Beutelmull; Spanish: Topo marsupial.

physical characteristics

As for N. typhlops, but with smaller nose shield and claws and reduced lower teeth.

distribution

Northwestern Western Australia, in the vicinity of Eighty Mile Beach.

Notoryctes caurinus

habitat

Sandy desert.

behavior

Lives alone; burrows in loose sand using swimming action, but creates no persistent burrow system, surfaces very occasionally.

feeding ecology and diet

Mostly insect larvae.

reproductive biology

Nothing is known.

conservation status

Endangered.

significance to humans

None known.

Resources

Books

Aplin, K. P., and M. Archer. "Recent Advances in Marsupial Systematics with a New Syncretic Classification." In Possums and Opossums: Studies in Evolution. Sydney: Surrey Beatty & Sons and Royal Zoological Society of New South Wales, 1987.

Nowak, R. "Order Notoryctemorphia." In Walker's Mammals of the World. 6th ed. Vol. 1. Baltimore and London: Johns Hopkins University Press, 1999.

Strahan, R. The Mammals of Australia. Carlton, Australia: Reed New Holland, 1995.

Organizations

Australian Museum. 6 College Street, Sydney, New South Wales 2010 Australia. Phone: (2) 9320 6000. Web site: <http://www.amonline.net.au>

Riversleigh Fossils Centre. P.O. Box 815, Mount Isa, Queensland 4825 Australia. Phone: (7) 4749 1555. E-mail: riversleigh@mountisa.qld.gov.au Web site: <http://www.riversleigh.qld.gov.au>

Amy-Jane Beer, PhD