Thorny Devils

Last updated: Friday 27 May, 2016

(Moloch horridus)

The Thorny Devil is at home on our Charles Darwin Reserve, WA. Photo Kurt Tschirner.
The Thorny Devil is at home on our Charles Darwin Reserve, WA. Photo Kurt Tschirner.
The Thorny Devil is marred with a wicked common name, and its Latin species name horridus doesn’t seem much better. In reality, it’s a slow-moving ant-eater, and horridus means bristly, referring to the reptile’s erect stance!

The Thorny Devil is a diurnal (day-active) reptile reaching 20cm in length. They're covered in thorny spines and sport a 'pretend' head on the back of their neck, which is thought to warn off predators.

Many of our staff love Thorny Devils. Photo Nella Lithgow at Cravens Peak, Qld.
Many of our staff love Thorny Devils. Photo Nella Lithgow at Cravens Peak, Qld.
Amazingly, they can change colour to blend into their surrounds. They can appear grey, red, orange and yellow.

Their gait is also remarkable: tail lifted, they walk along with slow, jerky movements backwards and forwards. This might be a defense mechanism to confuse predators when they're spotted in the open.

How do these lizards survive in water-parched arid Australia? During the night dew condenses on their bodies, and in the morning they brush up against dew-covered grass. Then the hygroscopic (moisture-attracting) grooves between their scales channel this water to their mouths!

The extraordinary contours of the Thorny Devil. Photo A.J.Emmott.
The extraordinary contours of the Thorny Devil. Photo A.J.Emmott.
The same process occurs when it rains. Essentially, capillary action allows the lizard to suck water from all over its body – an amazing adaptation!

The species holds cultural importance for many Aboriginal groups – for example, the Anmatyerre/Alyawarr people of the Northern Territory have a dreaming story surrounding the species.

Where does the Thorny Devil Live?

Their range covers most of arid Australia – large parts of Western Australia, the southern half of the Northern Territory, South Australia and western Queensland. They live in dry sand country, spinifex grasslands and scrub.

A fearsome sight up close! Photo A.J.Emmott.
A fearsome sight up close! Photo A.J.Emmott.
It may be a well-known species, but scientists are still unsure about its distribution and population size. As such, the International Union for the Conservation of Nature (IUCN) is yet to make an assessment about the conservation status of the Thorny Devil.

Behaviour

Head-bobbing and leg-waving is how a male Thorny Devil attracts a mate. Courtship complete, the female then lays 3 to 10 eggs in a chamber burrowed 30cm deep in the soil. Depending on the temperature, the eggs hatch after three to four months. Young start eating almost immediately.

Thorny Devils eat ants. In the morning and late afternoon they locate a trail and lap them up with their short, sticky tongue. In one day an individual can eat thousands of ants! This diet seems to suit them just fine: they can live to be 20 years old in the wild.

Threats

They can be very well camouflaged. Photo Leanne Hales at Eurardy Reserve, WA.
They can be very well camouflaged. Photo Leanne Hales at Eurardy Reserve, WA.
Natural predators include Goannas and predatory birds like the Brown Falcon. Being entirely reliant on ant populations, the Thorny Devil is vulnerable to habitat loss and disturbance. Being ectotherms (which get their body heat from external sources) they’re at risk of being run over while basking on warm roads.

What’s Bush Heritage doing?

Thorny Devils are found on our Charles Darwin, Hamelin and Eurardy reserves in Western Australia, as well as Cravens Peak and Ethabuka in Queensland.

They’re also found in the Birriliburu Indigenous Protected Area where we partner with the Martu people – Traditional Owners of this country – to support important work such as reinstating traditional fire patterns, Bilby monitoring and conducting baseline fauna surveys.

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