Thorny Devil Fact File
With an appearance unlike any other Australian lizard the thorny devil is instantly recognizable. Their short and stout body is covered with dark or reddish brown scales. A range of yellow crossbars run through this and a yellow stripe runs down the length of the body starting just behind the eye. The tail is brown with white striping. Their legs are white and the underside is red with marbled patterning.
Their colouration mimics the sandy deserts of central Australia which they inhabit and are an adaptation to help avoid predators.
They are also able to vary their colouration slightly to blend in and avoid predators. This includes turning almost black along with darker or lighter shades of their normal colouration.
Their body is covered with spikes including a large one above each eye. The eye is coloured black and sits on the sides of the head. Behind the head is a large brown growth which is a false head for protection against predators.
An average adult is 18cm (7.1in) long and they weigh just 25-50g (0.8-1.75oz). Females are larger than males.
Thorny devils solely feed on small black ants. They will find a trail of ants which are heading out to forage and pick off the ants as they walk. In a single feed they may eat in excess of 2,000 ants. The ants are licked up with the tongue.
One of the biggest issues for keeping the thorny devil in zoos is their specialized diet and as such very few are home to this species.
To obtain water they have a unique adaptation. In the morning they will rub up against plants which have collected dew over night. This rubbing motion moves the water between the spikes that cover their body and up to the mouth for them to drink.
In an extreme case of dry weather where little water is available they may bury themselves in sand and the moisture then comes out of the sand in to their mouth in a similar fashion.
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Australia is the native home of the thorny devil. Here they are found throughout the West of the country covering most of the inland areas in Western Australia, the Northern Territory and South Australia along with a small portion of Queensland.
The thorny devil is found primarily in arid or semi-arid deserts. They do also inhabit shrubland and woodland as well.
Mating takes place from late winter right through to the start of summer.Males will approach the female and bob their head before mounting the female to see if she is receptive. Females will on occasion reject the male which they do by rolling over.
The female will put on a significant amount of weight prior to mating. This is used to provide nutrients for the eggs. Up to 40% of their body weight may be lost once they lay their eggs.
Females will dig a tunnel which is up to 15cm (5.9in) long in to which they deposit 3-10 eggs. This tunnel is then filled in with sand and the eggs are left to incubate.
Incubation take three to four months. Following this the young will eat their egg casing before coming to the surface.
The young may take 5 years before they reach their adult size.
The thorny devil moves around using a slow, swaying gait. While walking the tail is raised up at an almost right angle to the body. It is believed this movement serves to confuse a predator that may spot them.
Thorny devils are active by day. During extreme periods of heat and cold they will become inactive and spend their time in a burrow they dig.
Predators and Threats
Predators of the thorny devil include goannas and birds of prey.
When threatened by a predator the thorny devil will dip their head down and present the false ‘head’ which is a lump of fat on the back of their head. This part of the body can recover quickly if injured so if they are being attacked they would rather it be there.
They are also able to puff up their body using a breath of air. Once complete they look bigger to predators and are harder to swallow which may help protect them.
Thorny devils are particularly vulnerable to attack when eating as they stay in one place for long periods of time. Their colouration is helpful as it allows them to blend in with their surroundings and as such they are harder to spot.
Humans affect the thorny devil through habitat destruction and vehicle strikes. They come in to contact with vehicles as they sit on roads to warm up easier.
Their latin name ‘horridus’ translates as bristly and is used to describe their erect stance. The moloch portion comes from canaanite god, Moloch.
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Bush Heritage Australia. 2020. Thorny Devils - Bush Heritage Australia. [online] Available at: <https://www.bushheritage.org.au/species/thorny-devils> [Accessed 4 June 2020].
Dewey, T. 2009. "Moloch horridus" (On-line), Animal Diversity Web. Accessed June 04, 2020 at https://animaldiversity.org/accounts/Moloch_horridus/
Doughty, P., Melville, J., Craig, M. & Sanderson, C. 2017. Moloch horridus. The IUCN Red List of Threatened Species 2017: e.T83492011A83492039. Downloaded on 04 June 2020.
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