Deep dive 3 min read
The Thorny Devil’s Fake Head (and How It Drinks Through Its Skin)
The thorny devil has a fake head on its neck and drinks water through its skin. Here's how Australia's spikiest lizard pulls off both tricks.
The thorny devil looks like a cactus that learned to walk. Every part of it is covered in spikes. But its two best tricks have nothing to do with being prickly: it has a spare head, and it drinks with its skin.
The fake head
On the back of its neck, the thorny devil has a round, spiky lump. When a predator such as a bird comes close, the lizard tucks its real head down between its front legs. What’s left on top looks exactly like a head: the spiky knob.
If the predator bites, it gets a mouthful of thorns instead of a skull. The lump is fat tissue, so a bite there does far less damage than a bite to the real head.
Bite here, please. The real head is busy hiding.
How does the thorny devil drink through its skin?
The desert of central Australia is dry, so the thorny devil can’t count on puddles. Instead, its skin works like a sponge with plumbing:
- Tiny grooves run between its scales all over the body.
- Water soaks in when the lizard stands in damp sand, touches dew or gets rained on.
- Capillary action pulls the water along the grooves, the same force that makes water creep up a paper towel.
- The grooves lead to its mouth, where it swallows the water.
Scientists have watched thorny devils shovel damp sand onto their backs to collect more water. It’s one of the cleverest water-saving systems in the animal world.
Strange but trueA thorny devil eats only small ants, and lots of them. It can eat thousands in a single day, flicking them up one at a time with its sticky tongue.
What else makes it strange?
- It changes colour: pale yellow and red when warm, darker and duller when cold or scared.
- It walks like a robot: a slow, jerky, rocking walk that may help it look like a twig moving in the wind.
- It puffs up: when grabbed, it fills its body with air to look bigger and harder to swallow.
How big is a thorny devil?
Small. Adults are about 6 to 8 in (15 to 20 cm) long, with females a bit bigger than males. That’s about the length of a pencil. It can live up to about 20 years.
Can you keep a thorny devil as a pet?
No. Thorny devils are protected in Australia, and their ant-only diet makes them almost impossible to keep healthy in captivity. The best way to see one is on a road trip through central or western Australia on a warm day.
Meet more of Australia’s oddballs in Strange Animals of Australia.
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