THE DEVIL WENT DOWN UNDER

Will we ever get to see thorny devils on this side of the world?

Isolated from Gondwana some 100 million years ago, Australia has been responsible for producing some of the most obscure and unusual animals on the planet. The thorny devil (Moloch horridus) is very possibly the strangest of these animals and one of the weirdest-looking vertebrates on the planet. Its quirky adaptations are the lizard’s greatest strength, allowing it to inhabit some of the most hostile environments on the planet. In fact, thorny devils are so specially adapted that it is practically impossible to ever keep this species in captivity outside of Australia.

Natural history

The name ‘Moloch horridus’ comes from the Caanite god ‘Moloch’ from John Milton’s epic, Paradise Lost. Horridus is also loosely translated from latin to mean ‘rugged’ or ‘dreadful’. Despite their fearsome appearance, these lizards only grow to around 20cm in length and live exclusively on a diet of ants. They are found across a huge area of Australia that extends right from Australia’s West Coast, deep into the heart of the country, covering areas in South Australia, Western Australia, Northern Territory and some of Queensland. However, they only inhabit areas made up of sandy soil or sandy loam soil.

Aside from the stunning spines they possess, thorny devils are also variable in their colouration. Usually, a brown or olive animal in the morning, these lizards will end up ‘firing up’ as the heat intensifies, bringing out vibrant orange and yellow pigment later in the day. Observations also suggest their thermoregulation is conducted largely through posture. When they hope to warm up, they will place their smooth bellies onto warm surfaces and when they wish to cool down, will use both arms to hold their body off the ground, by grasping onto spinifex grass.

Thorny devils have also developed a ‘false head’ that they use as a defence mechanism. This bony mass on their neck confused scientists for a long time as it cannot be dropped or detached. Instead, it is thought that the sheer size of this intimidates smaller predators and its obvious lack of vital organs such as the brain makes it a preferable target should the lizard be attacked. The ‘thorns’ of the thorny devil are also made of keratin and are genuinely sharp. Skin that is shed from atop the thorns retains its conical shape, making the shed ‘thorns’ of the thorny devil just as aesthetically interesting as the lizard itself.

Daniel Rumsey is a Keeper at The Australian Reptile Park. His wild observations of thorny devils add some realism to the mystical appearance of these animals. Dan explained: “Thorny devils are found in semi-arid grasslands and along sand ridge deserts. In the areas I have encountered them, they seem to occur in fairly good numbers.” The IUCN recognises thorny devils as ‘Least Concern’ due to their wide distribution. However, their strict diet of ants means they are extremely reliant on a healthy ecosystem, leading some to consider localised populations as ‘vulnerable’.

Dan continued: “In saying that, the majority you find are animals struck and killed by cars. These aren’t the only threats that this species faces in the wild. Monitor species and birds of prey will predate on them. The thorns are no match for a voracious varanid or power beak of a raptor.”

Their iconic appearance means that thorny devils are often an interesting subject for enthusiasts all over the world. As a species that inhabits such harsh conditions, thorny devils can be the catalyst for much needed conservation efforts in remote areas, despite their seemingly abundant numbers. Dan continued: “I believe they are well received as an iconic Australian species which sparks a lot of research and interest from both the scientific community and the general public. This would have to be one of the main target species of any budding reptile enthusiast. I think there are lots of new areas of study that could be interesting around this species. They are a wonderful example of convergent evolution, and we see this more and more across many taxa. There is a vast space to continue to gain knowledge in this vast topic.”