Thorny devil

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Thorny devil
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Iguania
Family: Agamidae
Subfamily: Amphibolurinae
Genus: Moloch
Gray, 1841
M. horridus
Binomial name
Moloch horridus
Gray, 1841
Moloch horridus distribution map.png
Distribution of Moloch horridus

Acanthosaura gibbosus

The thorny devil (Moloch horridus), also known commonly as the mountain devil, thorny lizard, thorny dragon, and moloch, is a species of lizard in the family Agamidae. The species is endemic to Australia. It is the sole species in the genus Moloch. It grows up to 21 cm (8.3 in) in total length (including tail), with females generally larger than males.



The thorny devil was first described by the biologist John Edward Gray in 1841. While it is the only species contained in the genus Moloch, many taxonomists suspect another species might remain to be found in the wild. [2] The thorny devil is only distantly related to the morphologically similar North American horned lizards of the genus Phrynosoma. This similarity is usually thought of as an example of convergent evolution.

The names given to this lizard reflect its appearance: the two large horned scales on its head complete the illusion of a dragon or devil. The name Moloch was used for a deity of the ancient Near East, usually depicted as a hideous beast. [3] The thorny devil also has other nicknames people have given it such as the "devil lizard", "horned lizard", and the "thorny toad". [4]


The thorny devil grows up to 21 cm (8.3 in) in total length (including tail), [5] and can live for 15 to 20 years. The females are larger than the males. Most specimens are coloured in camouflaging shades of desert browns and tans. These colours change from pale colours during warm weather to darker colours during cold weather. The thorny devil is covered entirely with conical spines that are mostly uncalcified.

A thorny devil in Western Australia Thorny devil pale.jpg
A thorny devil in Western Australia

An intimidating array of spikes covers the entire upper side of the body of the thorny devil. These thorny scales also help to defend it from predators. Camouflage and deception may also be used to evade predation. This lizard's unusual gait involves freezing and rocking as it moves about slowly in search of food, water, and mates. [2]

The thorny devil also features a spiny "false head" on the back of its neck, and the lizard presents this to potential predators by dipping its real head. The "false head" is made of soft tissue. [6]

The thorny devil's scales are ridged, enabling the animal to collect water by simply touching it with any part of the body, usually the limbs; the capillary principle allows the water to be transported to the mouth through the skin. [2]

Distribution and habitat

Illustration from Lydekker's The Royal Natural History MolochLyd.jpg
Illustration from Lydekker's The Royal Natural History
Thorny devil underside, Western Australia Thorny Devil crop.jpg
Thorny devil underside, Western Australia

The thorny devil usually lives in the arid scrubland and desert that covers most of central Australia, sandplain and sandridge desert in the deep interior and the mallee belt.

The habitat of the thorny devil coincides more with the regions of sandy loam soils than with a particular climate in Western Australia. [7]


The thorny devil is covered in hard, rather sharp spines that dissuade attacks by predators by making it difficult to swallow. It also has a false head on its back. When it feels threatened by other animals, it lowers its head between its front legs, and then presents its false head. Predators that consume the thorny devil include wild birds and goannas.


The thorny devil mainly subsists on ants, especially Ochetellus flavipes and other species in the Iridomyrmex or Ochetellus genera. [8] Thorny devils often eat thousands of ants in one day. [2]

The thorny devil collects moisture in the dry desert by the condensation of dew. This dew forms on its skin in the early morning as it begins to warm outside. Then the dew is channeled to its mouth in hygroscopic grooves between its spines. [9] During rainfalls, capillary action allows the thorny devil to absorb water from all over its body. Capillary action also allows the thorny devil to absorb water from damp sand. Absorption through sand is the thorny devil's main source of water intake. [10]


The female thorny devil lays a clutch of three to ten eggs between September and December. She puts these in a nesting burrow about 30 cm underground. The eggs hatch after about three to four months. [11]

The popular appeal of the thorny devil is the basis of an anecdotal petty scam. American servicemen stationed in Southwest Australia decades ago (such as during World War II) were supposedly sold the thorny fruits of a species of weeds, the so-called "double gee" ( Emex australis ), but those were called "thorny devil eggs" as a part of the scam.[ citation needed ] Thorny devils have been kept in captivity. [2]

Related Research Articles

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Moloch is the name of a god associated with child sacrifice in the Hebrew Bible and with Phoenician religion.

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<i>Saara hardwickii</i> Species of lizard

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M. horridus may refer to:

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<i>Ctenophorus parviceps</i> Species of lizard

Ctenophorus parviceps, commonly known as the Gnaraloo heath dragon or northwestern heath dragon is a species of agamid lizard occurring in pale coastal sands and shell grit with open heaths and beach spinifex, between the North West Cape and Carnarvon, Western Australia and on Bernier Island. The Gnaraloo Heath Dragon is a lizard that can be found along the coast of Western Australia between Exmouth Gulf and Shark Bay, and is also known as the Northwestern Heath Dragon. It is native to Australia and usually inhabits sandy coastal dunes. The species’ longevity is 3-50 years and its population density is extremely low. The Gnaraloo Heath Dragon is a member of the Agamidae family, which contains 15 genuses. The lizard is under the Ctenophorus genus which has up to 33 species. This genus shows the most morphological and ecological diversity out of the three large agamid genera. 83% of the lizards in this genus lack a crest, while 17% possess crests. They are smaller than most agamids but do have relatively large heads. The Gnaraloo Heath Dragon can be differentiated from related species by a series of spines on the tail’s base, a pale-grey brown broad vertebral band along its back, and hour-glass bars extending upwards to meet the pale vertebral band. It is usually 45mm in terms of length, measuring from snout to vent.


  1. Doughty, P., Melville, J., Craig, M. & Sanderson, C. (2017). "Moloch horridus". IUCN Red List of Threatened Species . 2017. Retrieved 21 February 2021.CS1 maint: uses authors parameter (link)
  2. 1 2 3 4 5 Browne-Cooper, Robert; Bush, Brian; Maryan, Brad; Robinson, David (2007). Reptiles and Frogs in the Bush: Southwestern Australia. University of Western Australia Press. pp. 46, 65, 158. ISBN   978-1-920694-74-6.
  3. Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). "Moloch horridus" in The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. p. 182. ISBN   978-1-4214-0135-5.
  4. Thorny Devil Lizard – Prickly Desert Ant-Eater.
  5. Boulenger GA (1885). "Moloch horridus" in Catalogue of the Lizards in the British Museum (Natural History). 2nd Ed. Vol. I. ... Agamidæ.. Taylor and Francis. pp. 411–412.
  6. Bell, Christopher; Mead, Jim; Swift, Sandra (2009). "Cranial osteology of Moloch horridus (Reptilia: Squamata: Agamidae)". Records of the Western Australian Museum. 25 (Part 2): 201–237. doi: 10.18195/issn.0312-3162.25(2).2009.201-237 .
  7. Pianka ER, Pianka HD (1970). "The ecology of Moloch horridus (Lacertilia: Agamidae) in Western Australia". Copeia. 1970 (1): 90–103. doi:10.2307/1441978. JSTOR   1441978.
  8. Australia's Thorny Devil , retrieved 31 October 2007
  9. Bentley PJ, Blumer FC (1962). "Uptake of water by the lizard, Moloch horridus". Nature. 194 (4829): 699–700. Bibcode:1962Natur.194..699B. doi:10.1038/194699a0. PMID   13867381. S2CID   4289732.
  10. Knight, Kathryn (2016). "How thorny devils tap damp sand to slake thirst". The Journal of Experimental Biology. 219 (21): 3309.1–3309. doi: 10.1242/jeb.151407 . S2CID   89521720.
  11. Pianka ER (1997). "Australia's thorny devil". Reptiles. 5 (11): 14–23.

Further reading