For the Kids

Thorny Devil (Moloch horridus)

What does it look like?

Thorny devil (Moloch horridus)
Thorny devil distribution map

With its many rows of curved spikes, the thorny devil looks a force to be reckoned with! The lizard’s scientific name, Moloch horridus, was derived from Milton’s poem Paradise Lost. In the poem the Canaanite god Moloch is described as a “horrid king besmeared with blood of human sacrifice”. But the thorny devil’s fearsome appearance belies its true nature. Less than 20 cm long, this slow-moving creature feeds solely on ants.

Attractively dappled with yellow, orange, brown and white markings, the thorny devil can change its colour according to the amount of sunlight and its surroundings. Combined with its unpalatable spines, the lizard’s camouflage provides an effective defence against predators. But scientists are still unsure about the purpose of the large “horns” above each eye and the strange spiked hump behind the lizard’s head. The hump, which looks a bit like a second head, is probably a defence mechanism lowered to distract pecking predators such as birds. The horns may be used to store body fat or water.

Where does it live?

The thorny devil is found throughout the arid regions of Western Australia, the Northern Territory, south-western Queensland and western South Australia, living in sand, spinifex grasslands and scrub. It is very common throughout the Shark Bay World Heritage Area, especially in the red sands on Peron Peninsula, and at Nanga and on the coastal highway south of Carnarvon. Ideally adapted to its harsh environment, it uses tiny channels between the scales on its belly and legs to collect morning dew and water from damp sand. The water travels up these channels by capillary action to the lizard’s mouth.

How does it breed?

The thorny devil can live for at least twenty years and starts breeding at three years of age. Like other dragon lizards it attracts a mate with elaborate courtship rituals, including leg-waving and head-bobbing! In November and December the female lays a clutch of 3–10 eggs in a chamber burrowed up to 30 cm below the surface. Incubation depends on weather conditions, with warmer temperatures reducing hatching time from 18 weeks to about 13 weeks. Once hatched, the young lizards start eating ants almost immediately. Oblivious to the ants’ bites, they lie on an ant trail or nest and may lick up 1,000 ants in a single meal!

Any threats to its survival?

Like all reptiles thorny devils are ectotherms, deriving their body heat from external sources. They are often seen basking on roads in the early morning or late afternoon – and can be mistaken for twigs. Please keep a lookout for these animals while driving to avoid running them over. Thorny devils are protected under the Wildlife Conservation Act, so admire them but leave them in peace.

For more information about Western Australian wildlife check out the WA Museum Fauna Base website.

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Thorny devil close up Thorny devil close up2
Thorny devils have a large spiked hump above their head.
The purpose of this structure is uncertain.
Scales cover the entire surface of the thorny devil's body.

Shark Bay wildlife fact sheets