View source for Biology:Thorny devil

{{Short description|Species of lizard}}
{{pp-semi-indef}}
{{Use Australian English|date = September 2011}}
{{speciesbox
| name = Thorny devil
| image = Thornydevil.jpg
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Doughty, P. |author2=Melville, J. |author3=Craig, M. |author4=Sanderson, C. |date=2017 |title=''Moloch horridus'' |volume=2017 |page=e.T83492011A83492039 |doi=10.2305/IUCN.UK.2017-3.RLTS.T83492011A83492039.en |access-date=19 November 2021}}</ref>
| display_parents = 2
| genus = Moloch
| parent_authority = Gray, 1841
| species = horridus
| authority = Gray, 1841
| synonyms = ''Acanthosaura gibbosus''
| range_map = Moloch_horridus_distribution_map.png
| range_map_caption = Distribution of ''Moloch horridus''
}}

The '''thorny devil''' ('''''Moloch horridus'''''), also known [[Biology:Common name|commonly]] as the '''mountain devil''', '''thorny lizard''', '''thorny dragon''', and '''moloch''', is a [[Biology:Species|species]] of [[Biology:Lizard|lizard]] in the family [[Biology:Agamidae|Agamidae]]. The species is [[Biology:Endemism|endemic]] to {{wipe|Australia}}. It is the [[Biology:Monotypic taxon|sole species]] in the [[Biology:Genus|genus]] '''''Moloch'''''. It grows up to {{convert|21|cm|in|abbr=on}} in total length (including tail), with females generally larger than males.

==Taxonomy==
The thorny devil was first [[Biology:Species description|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.<ref name="Browne-Cooper"/> The thorny devil is only distantly related to the [[Biology:Morphology|morphologically]] similar [[Earth:North America|North America]]n [[Biology:Horned lizard|horned lizard]]s of the genus ''Phrynosoma''. This similarity is usually thought of as an example of [[Biology:Convergent evolution|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 [[History:Ancient Near East|ancient Near East]], usually depicted as a hideous beast.<ref>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}}.</ref> The thorny devil also has other nicknames people have given it such as the "devil lizard", "horned lizard", and the "thorny toad".<ref>[http://www.factzoo.com/reptiles/lizards/thorny-devil-lizard.html Thorny Devil Lizard – Prickly Desert Ant-Eater]. factzoo.com</ref>

==Description==
The thorny devil grows up to {{convert|21|cm|in|abbr=on}} in total length (including tail),<ref>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.</ref> 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.

[[File:Thorny devil pale.jpg|thumb|left|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. [[Biology:Camouflage|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.<ref name="Browne-Cooper"/>

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.<ref>{{cite journal |last1=Bell |first1=Christopher |last2=Mead |first2=Jim |last3=Swift |first3=Sandra |title=Cranial osteology of ''Moloch horridus'' (Reptilia: Squamata: Agamidae) |journal=Records of the Western Australian Museum |date=2009 |volume=25 |issue=Part 2 |pages=201–237 |doi=10.18195/issn.0312-3162.25(2).2009.201-237 |doi-access=free }}</ref>

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; [[Physics:Capillary action|capillary action]] transports the water to the mouth through channels in its skin.<ref name="Browne-Cooper">{{cite book|author1=Browne-Cooper, Robert|author2=Bush, Brian|author3=Maryan, Brad|author4=Robinson, David|title=Reptiles and Frogs in the Bush: Southwestern Australia|year=2007|publisher=University of Western Australia Press|isbn= 978-1-920694-74-6|pages=46, 65, 158}}</ref> 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.<ref name="Comanns3">{{cite journal |last1=Comanns |first1=Philipp |last2=Esser |first2=Falk J. |last3=Kappel |first3=Peter H. |last4=Baumgartner |first4=Werner |last5=Shaw |first5=Jeremy |last6=Withers |first6=Philip C. |title=Adsorption and movement of water by skin of the Australian thorny devil (Agamidae: Moloch horridus) |journal=Royal Society Open Science |date=September 2017 |volume=4 |issue=9 |page=170591 |doi=10.1098/rsos.170591 |pmid=28989762 |pmc=5627102 |bibcode=2017RSOS....470591C }}</ref> 
*The lizard rubs its body against the moist substrate and shovels damp sand onto its back, the outer epidermis layer equipped to draw in cutaneous moisture. 
*The [[Biology:Keratin|keratinous fibered]] epidermis is hydrophilic with hexagonal microstructures on the scale surfaces. When trace amounts of water contact its skin (pre-wetting) these microstructures fill with water, the skin surface becoming [[Chemistry:Superhydrophilicity|superhydrophilic]].  This allows moisture to spread across wider surface areas, yielding faster uptake, as water is collected via capillary action in small channels located between its scales. 
*Captured water is transported passively via capillary action in semi-tubular channels located beneath the partially overlapping scales, in an asymmetric and interconnected system that extends over the lizard's entire body surface.  The channels terminate at the mouth where active ingestion (drinking) is observable by jaw movements when moisture is plentiful, e.g. water puddles.

The same hydrophilic moisture-harvesting physiology is characteristic in the [[Biology:Texas horned lizard|Texas horned lizard]] (''Phrynosoma cornutum''), roundtail horned lizard (''Phrynosoma modestum''), desert horned lizard (''Phrynosoma platyrhinos''), Arabian toad-headed agama (''[[Biology:Phrynocephalus arabicus|Phrynocephalus arabicus]]''), sunwatcher toadhead agama (''[[Biology:Phrynocephalus helioscopus|Phrynocephalus helioscopus]]''), ''[[Biology:Phrynocephalus horvathi|Phrynocephalus horvathi]]'', yellow-spotted agama (''Trapelus flavimaculatus''), ''Trapelus pallidus'' and desert agama (''[[Biology:Trapelus mutabilis|Trapelus mutabilis]]'').<ref name="Comanns2b">{{cite journal |last1=Comanns |first1=Philipp |title=Passive water collection with the integument: mechanisms and their biomimetic potential |journal=Journal of Experimental Biology |date=May 2018 |volume=221 |issue=10 |page=Table 1 |doi=10.1242/jeb.153130|pmid=29789349 |doi-access=free }}</ref>

==Distribution and habitat==
[[Image:MolochLyd.jpg|thumb|Illustration from Lydekker's ''The Royal Natural History'']]
[[Image:Thorny Devil crop.jpg|thumb|upright|Thorny devil underside, Western Australia]]
The thorny devil usually lives in the arid scrubland and [[Earth:Desert|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 [[Earth:Loam|loam]] soils than with a particular climate in Western Australia.<ref>{{cite journal|author=[[Biography:Eric Pianka|Pianka ER]], Pianka HD|year=1970|title=The ecology of ''Moloch horridus'' (Lacertilia: Agamidae) in Western Australia|journal=Copeia|volume=1970|issue=1|pages=90–103|doi=10.2307/1441978|jstor=1441978}}</ref>

==Self-defense==
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 [[Biology:Goanna|goanna]]s.

==Diet==
The thorny devil mainly subsists on ants, especially ''[[Biology:Ochetellus flavipes|Ochetellus flavipes]]'' and other species in the ''[[Biology:Camponotus|Camponotus]]'', ''[[Biology:Ectatomma|Ectatomma]]'',<ref name="animaldiversity.org">{{Cite web|url=https://animaldiversity.org/accounts/Moloch_horridus/|title = Moloch horridus (Thorny Devil, Mountain Devil)| website=[[Biology:Animal Diversity Web|Animal Diversity Web]] }}</ref> ''[[Biology:Iridomyrmex|Iridomyrmex]]'' (especially ''Iridomyrmex rufoniger''),<ref name="animaldiversity.org"/> ''[[Biology:Monomorium|Monomorium]]'',<ref name="animaldiversity.org"/> ''[[Biology:Ochetellus|Ochetellus]]'', ''[[Biology:Pheidole|Pheidole]]'', or ''[[Biology:Polyrhachis|Polyrhachis]]''<ref name="animaldiversity.org"/> genera.<ref>{{citation |url=http://uts.cc.utexas.edu/~varanus/moloch.html |title=Australia's Thorny Devil |access-date=2007-10-31 }}</ref> Thorny devils often eat thousands of ants in one day.<ref name="Browne-Cooper"/>

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 [[Physics:Capillary action|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.<ref>{{cite journal|doi=10.1242/jeb.151407|title=How thorny devils tap damp sand to slake thirst|year=2016|last1=Knight|first1=Kathryn|s2cid=89521720|journal=The Journal of Experimental Biology|volume=219|issue=21|pages=3309.1–3309|doi-access=free}}</ref>

==Reproduction==
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&nbsp;cm underground. The eggs hatch after about three to four months.<ref>{{cite journal|author=Pianka ER|year=1997|title=Australia's thorny devil|journal=Reptiles|volume=5|issue=11|pages=14–23}}</ref>

==Popular reference==
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 [[Social:World War II|World War II]]) were supposedly sold the thorny fruits of a species of weeds, the so-called "double gee" (''[[Biology:Emex australis|Emex australis]]''), but those were called "thorny devil eggs" as a part of the scam.{{citation needed|date=July 2015}} Thorny devils have been kept in captivity.<ref name="Browne-Cooper"/>

==References==
{{Reflist}}

==Further reading==
*{{cite journal|last1=Clemente|first1=Christofer|last2=Thompson|first2=Graham G.|last3=Withers|first3=Philip C|last4=Lloyd|first4=David|title=Kinematics, maximal metabolic rate, sprint and endurance for a slow-moving lizard, the thorny devil (''Moloch horridus'')|journal=Australian Journal of Zoology|date=2004|volume=52|issue=5|pages=487–503|doi=10.1071/ZO04026}}
*{{cite journal|last1=Meyers|first1=Jay|title=Prey capture kinematics of ant-eating lizards|journal=Journal of Experimental Biology|date=2005|volume=208|issue=Pt 1|pages=115–127|doi=10.1242/jeb.01345|pmid=15601883|id={{ProQuest|13293724}}|doi-access=free}}
*Cogger HG (2014). ''Reptiles and Amphibians of Australia, Seventh Edition''. Clayton, Victoria, Australia: CSIRO Publishing. xxx + 1,033 pp. {{ISBN|978-0643100350}}.
*Gray JE (1841). "Description of some new Species and four Genera of Reptiles from Western Australia discovered by John Gould, Esq." ''The Annals and Magazine of Natural History'', [''First Series'' ] '''7''': 86–91. (''Moloch'', new genus pp.&nbsp;88–89; ''M. horridus'', new species, p.&nbsp;89).
*Wilson, Steve; Swan, Gerry (2013). ''A Complete Guide to Reptiles of Australia, Fourth Edition''. Sydney: New Holland Publishers. 522 pp. {{ISBN|978-1921517280}}.

==External links==
*[http://digimorph.org/specimens/Moloch_horridus/head/ Digimorph: ''Moloch horridus'', thorny dragon body structure]
*[http://uts.cc.utexas.edu/~varanus/moloch.html Australia's Thorny Devil by Eric R. Pianka]
*[https://web.archive.org/web/20091025153154/http://www.kidcyber.com.au/topics/thornydev.htm Thorny Devil], www.kidcyber.com.au

{{Taxonbar|from=Q320665}}

[[Category:Agamidae]]

{{Sourceattribution|Thorny devil}}