Thorny Devil

The thorny devil is an Australian lizard easily recognizable from its spine-covered body. These spines play several vital roles for the lizard, from defense to helping it collect water for drinking to serving as a camouflage.

British biologist John Edward Gray first described this species in 1841. They are the only known species in their genus, Moloch. It has several other names like the devil lizard, the mountain devil, moloch, thorny dragon, or thorny lizard.

Description

Size: Length: 2.99 to 4.33 in (7.6 to 11 cm) Weight: 1.00 to 2.01 oz (28.5 to 57 g)

Body and Coloration: The females appear bigger in comparison to their male counterparts. The upper parts of these lizards’ bodies are covered with horned thorny scales with ridges, drawing a striking similarity to the mythical dragons or devils, hence the name. These spines are boneless, and their mandibular teeth have been designed in a way to cater to their insectivorous diet.

The skin color of the thorny devil varies with temperature. They are brown or olive early on in the day, becoming light yellow when temperatures rise later in the afternoon.

Range and Distribution

Thorny devils dwell in Australia’s Great Sandy Desert in regions with sandy soils.

Habitat

They are found in sand plain and ridge deserts consisting primarily of sandy soils, where spinifex grass is the primary form of vegetation.

Diet

These lizards are myrmecophages, i.e., their diet consists primarily of ants, eating around 1000 ants a day. They collect dew through the complicated structures on their body for drinking purposes.

Lifespan

Thorny devils live for about 20 years in their wild habitat.

Behavior

• They are semi-nomadic over a small area, dependent on the availability of ants. The movement of these diurnal lizards include leaving their burrows in the morning, warming themselves in the sand during the day, and visiting a specific site to excrete.
• Thorny devils have an unusual gait, sauntering, stopping to check their surroundings, and then rocking back and forth.
• These reptiles are bimodal, becoming inactive during the hottest and coldest months and showing the highest amount of activity during autumn.

Predators

The known predators of the thorny devil include Australian bustards, black-breasted buzzards, racehorse monitor lizards, and sand goannas.

Adaptations

How do they survive in the desert

The unique appearance of this lizard, be it its spiky body, color changing abilities or false head, help it immensely to survive in the hot desserts and even defend itself from its probable predators.

• Their primary adaptation as mentioned above is their thorny scales with a ridged pattern which help them drink water with ease. In fact, underneath the scales lie microscopic grooves that acts as a straw, helping the water to get transported to their mouth via their skin through the process of capillary action.
• The characteristic spikes or “thorns”, give them a fearful look, dissuading most predators from attacking them.
• There is a knob-like appendage or a “false head” behind its neck made of soft tissues, which it uses in defense to confuse its predators. Infact upon sensing a threat it hides its real head by tucking it in between the forelegs, making the false head visible to its foes.
• They can change their color as a form of camouflage, becoming darker in colder weather or when they are alarmed.
• Thorny devils have the ability to inflate their chests with air to make themselves harder for a predator to swallow.

Mating and Reproduction

While information about the mating period of these lizards is sparse, it is known that thorny devils breed and lay eggs from August to December. Males will approach females, bob their heads, and mount her if they think she seems receptive. Females will throw off unwanted males.

Life Cycle

The mother lays a clutch of 3-10 eggs between September and December. She puts the eggs in a nesting burrow 30 cm underground, hatching after about 3-4 months.

Newly hatched thorny devils weigh 1.8 g on average. They eat their egg casing before climbing out of the oviposition nest.

Conservation Status

The IUCN lists the thorny devil as “LC” or “Least Concern”.

Interesting Facts

• The scientific name of the thorny devil was inspired by John Milton’s poem “Paradise Lost”, in which the poet describes the Caananite God Moloch as a horrible king who was smeared with the blood of human sacrifice.
• As a part of a scam enacted decades ago, American servicemen stationed in Southwest Australia were supposedly sold the thorny fruits of a species of weeds as “thorny devil eggs”.