Thorny devil

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Thorny devil
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
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; capillary action transports the water to the mouth through channels in its skin. [2] The thorny devil is also equipped to harvest moisture in the dry desert following nighttime's extremely low temperatures and the subsequent condensation of dew. The process involves moisture contact, their hydrophilic skin surface structures with capillaries, and an internal transport mechanism. [7]

The same hydrophilic moisture-harvesting physiology is characteristic in the Texas horned lizard (Phrynosoma cornutum), roundtail horned lizard ( Phrynosoma modestum ), desert horned lizard (Phrynosoma platyrhinos), Arabian toad-headed agama ( Phrynocephalus arabicus ), sunwatcher toadhead agama ( Phrynocephalus helioscopus ), Phrynocephalus horvathi , yellow-spotted agama ( Trapelus flavimaculatus ), Trapelus pallidus and desert agama ( Trapelus mutabilis ). [8]

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. [9]


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 Camponotus , Ectatomma , [10] Iridomyrmex (especially Iridomyrmex rufoniger ), [10] Monomorium , [10] Ochetellus , Pheidole , or Polyrhachis [10] genera. [11] 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 by gravity and capillary action via the channels between its spines. 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. [12]


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. [13]

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

<span class="mw-page-title-main">Lizard</span> Informal group of reptiles

Lizard is the common name used for all squamate reptiles other than snakes, encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon.

<i>Phrynocephalus</i> Genus of lizards

Phrynocephalus is a genus which includes 33 species of small and medium-sized agamid lizards, commonly called toadhead agamas or toad-headed agamas, that inhabit open arid and semiarid environments of Asia and Eastern Europe. The systematics of this genus are very complicated with many controversial points of view about the unclear phylogeny of this group. All representatives of this genus have adopted the so-called "sit and wait" hunting strategy and they actively use visual orientation when watching for food. In general, the ecological niche and role of Phrynocephalus species in lizard communities of arid environments of Asia are poorly studied, but seem to be similar to that of Phrynosoma, Cophosaurus, Holbrookia, Uta, and Sceloporus in the New World, as well as Moloch in Australia.

<span class="mw-page-title-main">Horned lizard</span> Genus of reptiles

Phrynosoma, whose members are known as the horned lizards, horny toads, or horntoads, is a genus of North American lizards and the type genus of the family Phrynosomatidae. Their common names refer directly to their horns or to their flattened, rounded bodies, and blunt snouts.

<span class="mw-page-title-main">Desert horned lizard</span> Species of lizard

The desert horned lizard is a species of phrynosomatid lizard native to western North America. They are often referred to as "horny toads", although they are not toads, but lizards.

<span class="mw-page-title-main">Coast horned lizard</span> Species of lizard

The coast horned lizard is a species of phrynosomatid lizard endemic to Baja California Sur in Mexico. As a defense the lizard can shoot high pressure streams of blood out of its eyes if threatened.

<span class="mw-page-title-main">Flat-tail horned lizard</span> Species of lizard

The flat-tail horned lizard is a species of lizard in the family Phrynosomatidae. A species of reptile, it is endemic to the Sonoran desert of the southwestern United States and northwestern Mexico. Its multiple adaptations for camouflage help to minimize its shadow. The species is threatened, with a restricted range under pressure from human activities such as agriculture and development, and is specially protected in the United States.

<span class="mw-page-title-main">Roundtail horned lizard</span> Species of lizard

The roundtail horned lizard is one of the smaller species of horned lizard. Their specific epithet is from the Latin word modestum, meaning modest or calm. They are found in the United States, in western Texas, New Mexico eastern Arizona, southeastern Colorado and eight states in northcentral Mexico where they are referred to as "tapayaxtin".

<i>Phrynocephalus theobaldi</i> Species of lizard

Phrynocephalus theobaldi is a species of lizard in the family Agamidae. The species is endemic to Asia.

<span class="mw-page-title-main">Savigny's agama</span> Species of lizard

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<span class="mw-page-title-main">Erg agama</span> Species of lizard

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<span class="mw-page-title-main">Mexican horned lizard</span> Species of lizard

The Mexican horned lizard is a horned lizard species native to Mexico. Horned lizards are sometimes referred to as "horned toads" or "horny toads", although they are not toads. Compared to other members of the horned lizards, little is known about this species.

<span class="mw-page-title-main">Regal horned lizard</span> Species of lizard

The regal horned lizard is a horned lizard species native to Mexico and the Southwest United States.

<i>Phrynocephalus persicus</i> Species of lizard

Phrynocephalus persicus, commonly known as the Persian toad-headed agama, is a small diurnal desert lizard of the family Agamidae. It is the westernmost representative of the Central Asian genus of toad-headed agamas Phrynocephalus and is only known from deserts and semideserts of Iran and possibly Azerbaijan.

<span class="mw-page-title-main">Pygmy short-horned lizard</span> Species of lizard

The pygmy short-horned lizard is a species of small horned lizard in the family Phrynosomatidae. The species is native to the northwestern United States and adjacent southwestern Canada. Like other horned lizards, it is often called a "horned toad" or "horny toad," but it is not a toad at all. It is a reptile, not an amphibian.

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

Ctenophorus caudicinctus, commonly known as the ring-tailed dragon or ring-tailed bicycle-dragon is a native species of agamid lizard occurring in rocky ranges and outcrops of Australia. Ctenophorus caudicinctus is most commonly found in the Pilbara region and offshore islands of Western Australia. The ctenophorus has 28 known species in the northern, southern, and western parts of Australia. It is recognized to be the most speciose group of Australian agamids.

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Phrynocephalus forsythii, also known commonly as Forsyth's toadhead agama and Forsyth's toad-headed lizard, is a species of lizard in the family Agamidae. The species is endemic to China.

<i>Phrynocephalus guttatus</i> Species of lizard

Phrynocephalus guttatus, also known commonly as the spotted toadhead agama, the Saissan toad-headed agama, the Central Asian toadhead agama, and Salensky's toadhead agama, is a species of lizard in the family Agamidae. The species is native to southeastern Europe and western Asia. There are five recognized subspecies.


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  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.
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  4. Thorny Devil Lizard – Prickly Desert Ant-Eater.
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  7. Comanns, Philipp; Esser, Falk J.; Kappel, Peter H.; Baumgartner, Werner; Shaw, Jeremy; Withers, Philip C. (September 2017). "Adsorption and movement of water by skin of the Australian thorny devil (Agamidae: Moloch horridus)". Royal Society Open Science. 4 (9): 170591. Bibcode:2017RSOS....470591C. doi:10.1098/rsos.170591. PMC   5627102 . PMID   28989762.
  8. Comanns, Philipp (May 2018). "Passive water collection with the integument: mechanisms and their biomimetic potential". Journal of Experimental Biology. 221 (10): Table 1. doi: 10.1242/jeb.153130 . PMID   29789349.
  9. 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.
  10. 1 2 3 4 "Moloch horridus (Thorny Devil, Mountain Devil)". Animal Diversity Web .
  11. Australia's Thorny Devil , retrieved 31 October 2007
  12. 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.
  13. Pianka ER (1997). "Australia's thorny devil". Reptiles. 5 (11): 14–23.

Further reading