Thorny Devil Australian Thorny Dragon

thorny devil

Photo: Thorny devil displaying its warmed up colours

The thorny devil (Moloch horridus), also known as the thorny dragon, is a spiny lizard that lives in Australian Outback. Its upper body covered in sharp spines and it has a pretend head on the back of its neck, which it uses as a decoy to evade predators.


Thorny Devil - Description What Does a Thorny Dragon Look Like?

The thorny devil is a cold-blooded lizard (ectotherm) that regulates its body temperature using external sources such as sunlight or a warm surface. It usually starts the day with a drab olive-brown colour and as it warms up the thorny devil acquires its normal yellow, red and black colours. It has two small black eyes, each protected by a horny spike. Because the thorny devil is cold-blooded and needs to warm its body up, it is active only during the day.

Photo: Thorny devil displaying its morning colours

The thorny devil is about 76-110mm in length and weighs approximately 28-57g. The female is slightly larger than the male. Its most distinguishing feature is the intimidating spikes which cover its entire upper body. These thorns offer the animal protection from predators. If attacked, it puffs up its body and stiffens its spikes, making itself more difficult to swallow. The thorny devil also has another trick up its sleeve. It has a pretend head! Located on the top of its neck this fake head looks like a large knob with two spikes on it. When threatened, the lizard offers this fake head as a decoy and protects its real head between its front legs.


Thorny Devil - Walking Thorny Devil's Unusual Walk

Video: Thorny devil walking

The thorny devil has an unusual way of walking. It lifts its tail into a vertical position and oscillates back and forth as it moves. It is not understood why this animal does this. It has been suggested that this stop-start movement and the animal freezing in place as it walks may be to emulate a leaf. It looks somewhat like a leaf when viewed from above, making it more difficult for predatory birds to spot it.


Thorny Devil - Habitat Where Does the Thorny Devil Live?

The thorny devil lives in the spinifex grasslands, scrublands, deserts of the Australian Outback ranging from Western Australia, the Northern Territory, south-western Queensland through to western South Australia. They are found only in sandy or sandy loam soils. Thorny devils are semi-nomadic and not territorial. They do not have exclusive home ranges.


Thorny Devil - Diet What Does A Thorny Devil Eat?

Thorny devils are obligate myrmecophages—they eat black ants. They are ambush predators that find a suitable location where ants visit or pass through and then sit and wait to pick off their prey with their sticky tongues as they pass by. It is estimated that a thorny devil eats 600-3000 ants a day. It has special shearing teeth for slicing through the relatively hard chitin bodies of its ant diet.

Their average feeding rate is three ants per minute. Their maximum consumption rate is a blistering one ant per second. Their preferred dining times are in the morning and late afternoon when the temperature is above 24°c.

Living in the dry arid desserts, the thorny devil has evolved some ingenious ways to quench its thirst. It uses its body as a condenser of moisture and its skin like a drinking straw to collect water from dew and transport it to its mouth. On cool mornings dew collects on its skin. This dew is channelled by capillary action to its mouth along grooves between its spines. This capillary action is so effective that water even defies gravity and travels up its legs. Capillary action also allows the thorny devil to absorb moisture from damp sand. Absorption through sand is the thorny devil's primary source of water intake.


Thorny Devil - Reproduction & Life Cycle

Thorny devils mate once a year in the late winter through early summer (August to December). The courtship involves a lot of head bobbing and leg waving by the male. If she is receptive, he mounts her and deposits his sperm. The female usually digs a shallow burrow on a southern facing sand ridge, and deposits 3-10 eggs. She then covers up the burrow and abandons the site. Depending on the temperature of the soil, the eggs incubate for 90-132 days. The young hatchling's first meal is their own egg casing, which they eat before digging themselves out of the burrow.

Male and female thorny devils are the same size when they are born and grown at the same rate for the first year, after which the female outpaces the male in growth until they reach the age of 5 years.

Thorny devils live 6-20 years.


Thorny Devil -Predators & Threats What Kills Thorny Dragons?

Photo: Thorny devil on a main road

Even though thorny devils are well camouflaged and armoured, they fall prey to goannas and bird of prey. When threatened they freeze, even in mid-step. They will also puff themselves up and tuck their head between their front legs, making themselves more difficult to attack and swallow.

Thorny devils are also killed by humans who destroy their habitats and accidentally run over them as they bask on warm roads.


Conservation Status Is the Thorny Devil Endangered?

While their population numbers haven't been accurately established, the thorny devil population is believed to be unthreatened.

• Australian Animals — List of Native, Introduced, Endangered, Rainforest Fauna