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Mammals

Marsupial Mole

Notoryctes typhlops · also called itjaritjari, southern marsupial mole

Data Deficient carnivore Desert

The marsupial mole is a small golden animal that spends its life inside the sand of the Australian deserts. It has no working eyes and no external ears, it does not leave a tunnel, and it is seen so seldom that scientists cannot say how many there are or how long one lives.

Overview

Notoryctes typhlops is a marsupial, not a true mole, despite looking almost exactly like one. It lives in the deep, loose sand of the central and western Australian deserts, and it eats insect larvae, centipedes, and burrowing reptile eggs it meets while tunnelling.

Swimming through the ground

It does not dig an open burrow. It shoves forward with a horny nose shield and two spade-like foreclaws and lets the sand collapse behind it, leaving only a faint trace. It is blind and earless because neither sense works in solid sand, and its pouch opens backwards, like a wombat’s, so it does not fill with sand.

Convergent evolution

It matches the true moles of Eurasia and the golden moles of Africa in almost every detail of its body, yet all three are unrelated — three lineages that arrived at the same shape by burrowing.

Status

Data Deficient — genuinely unknown numbers. Most of what is known comes from a few dozen museum specimens, Aboriginal tracking knowledge, and traces in the sand. Introduced foxes and cats are the main known threat.

Marsupial Mole: common questions

Is the marsupial mole related to other moles?

No. The true moles of Europe, Asia, and North America are placental mammals in the order Eulipotyphla, alongside shrews and hedgehogs, and the golden moles of Africa are placental mammals too. The marsupial mole is a marsupial, and its closest living relatives are the bandicoots and bilbies. All three groups have independently evolved the same body plan, a stubby cylinder, tiny or absent eyes and ears, a short stiff tail, an armoured nose, and oversized clawed forelimbs for digging. It is one of the most complete examples of convergent evolution in mammals, three separate lineages on three continents converging on the same shape because burrowing through soil imposes the same demands on all of them.

How does it move through sand without a tunnel?

The marsupial mole lives in loose, dry, wind-blown desert sand, which cannot hold an open burrow the way clay or loam can. So instead of excavating a tunnel it stays in, the mole pushes its hardened nose shield and its two large spade-shaped foreclaws forward into the sand ahead, compacts and shoves the sand aside and past its body, and lets it fall back into place behind. The animal is effectively enclosed in sand at all times, moving through it like a swimmer, and it leaves no permanent structure, just a temporary zone of loosened sand that soon settles. This is why the moles are so hard to find and study.

Why does its pouch open backwards?

For the same reason a wombat's does. An animal that spends its life digging forward through soil or sand would, with a forward-opening pouch, constantly pack that pouch with debris and smother or abrade the young inside. Evolution has solved this the same way twice. The marsupial mole and the wombat, which are only distantly related among marsupials, both have a pouch that opens toward the hind legs, so it trails behind the digging action and stays clear of the spoil. The marsupial mole's pouch typically carries one or two tiny young.

If it is so rarely seen, how do we know anything about it?

From several sources pieced together. Museums hold a few dozen specimens collected over the past century and a half, many picked up dead on the surface or dug up by chance, and these have been dissected and scanned to work out the anatomy. Aboriginal peoples of the central deserts have long known the animal, calling it itjaritjari and kakarratul, and their tracking knowledge of its surface traces and behaviour is a major source of information. And researchers survey for the moles indirectly, by digging trenches across dune country and looking for the tell-tale backfilled trails they leave in the sand, and by analysing predator scats. Even so, the marsupial mole remains one of the most poorly understood mammals in the world.

Sources & further reading