View source for Common slow worm

{{short description|Species of legless lizard}}
{{Redirect-multi|3|Slow-worm|Slowworm|blindworm|the genus|Anguis}}
{{Speciesbox
| image = Anguidae.jpg
| taxon = Anguis fragilis
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name=iucn>{{cite iucn |author=Agasyan, A. |author2=Avci, A. |author3=Tuniyev, B. |author4=Crnobrnja-Isailović, J. |author5=Lymberakis, P. |author6=Andrén, C. |author7=Cogălniceanu, D. |author8=Wilkinson, J. |author9=Ananjeva, N.B. |author10=Üzüm, N. |author11=Orlov, N.L. |author12=Podloucky, R. |author13=Tuniyev, S. |author14=Kaya, U. |author15=Nettmann, H.K. |author16=Böhme, W. |author17=Sterijovski, B. |author18=Vogrin, M. |author19=Corti, C. |author20=Pérez Mellado, V. |author21=Sá-Sousa, P. |author22=Cheylan, M. |author23=Pleguezuelos, J. |author24=Tok, V. |author25=Sindaco, R. |author26=Borczyk, B. |author27=Schmidt, B. |display-authors =3 |year=2021 |title=Anguis fragilis |page=e.T47113126A744263 |doi=10.2305/IUCN.UK.2021-2.RLTS.T47113126A744263.en |access-date=9 June 2022}}</ref>
| authority = [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]
| range_map = Anguis fragilis distribution (countries only).png
| range_map_caption = Range of ''A. fragilis''
}}

The '''common slow worm''' ('''''Anguis fragilis''''') is a species of [[legless lizard]] native to western [[Eurasia]]. It is also called a '''deaf adder''', '''blindworm''', or regionally, a '''long-cripple''', '''steelworm''', and '''hazelworm.''' The "blind" in blindworm refers to the lizard's small eyes, similar to a [[blindsnake]] (although the slow worm's eyes are functional). The common slow worm, i.e. the species ''Anguis fragilis'', is often called simply "slow worm", though all species of the [[species complex]] comprising the genus ''[[Anguis]]'' are also called "slow worms".

Common slow worms are [[fossorial|semifossorial]]<ref>{{cite journal| url=http://www.ljmu.ac.uk/BIE/BIE_docs/ms_07-49.pdf| title=Feeding state and selected body temperatures in the slow worm| volume=18| pages=59–62| journal=Herpetological Journal| year=2008| access-date=2009-06-03| archive-url=https://web.archive.org/web/20090617154220/http://www.ljmu.ac.uk/BIE/BIE_docs/ms_07-49.pdf| archive-date=17 June 2009| url-status=dead}}</ref> (burrowing) [[lizard|lizards]] that spend much of their time hiding underneath objects. The skin of slow worms is smooth, with scales that do not overlap. Like many other lizards, they [[autotomy|autotomize]], meaning that they have the ability to shed their tails to escape predators. While the tail regrows, it does not reach its original length. In the UK, slow worms are commonly encountered in gardens and [[Allotment_(gardening)|allotments]], where they can be encouraged to enter and assist in the removal of pest insects by placing black plastic or providing places to shelter such as piles of logs, corrugated iron sheets, or tiles.<ref>{{cite web |last1=Vernon |first1=Jean |title=How can I help garden slow worms? |url=https://www.richardjacksonsgarden.co.uk/can-i-help-garden-slow-worms/ |website=Richard Jackson Garden |access-date=26 July 2022 |date=24 July 2019}}</ref> On warm days, one or more slow worms can often be found underneath these heat collectors. 

The name "slow worm" is only [[Folk etymology|contaminated by]] the word "slow". In Middle English, it was written "slowurm", from Old English "slāwyrm", where ''slā-'' means 'earthworm' or 'slow worm' and ''wyrm'' means "serpent, reptile".<ref>{{cite encyclopedia|title=Slowworm|encyclopedia=[[The American Heritage Dictionary of the English Language]]|year=2017|publisher=Houghton Mifflin Harcourt|url=https://www.ahdictionary.com/word/search.html?q=slowworm}})</ref><ref>{{Cite web|title=Anguis fragilis|url=https://reptile-database.reptarium.cz/species.php?genus=Anguis&species=fragilis|access-date=2021-04-07|website=The Reptile Database}}</ref> It is related to the Norwegian [[wikt:slo#Norwegian Nynorsk|slo]] or Swedish [[wikt:ormslå|ormslå]], of same meaning.

== Taxonomy ==
[[File:Anguis-distribution.png|left|thumb|Distribution of species of European slow worms]]
''Anguis fragilis'' was historically divided into two subspecies (''A. f. fragilis'' and ''A. f. colchica''). However, recent taxonomic classification has resulted in the categorisation of these as separate species:<ref name=":0">{{Cite web|title=Živa – Přehlížená rozmanitost slepýšů (Jiří Moravec, Václav Gvoždík)|url=https://ziva.avcr.cz/2019-5/prehlizena-rozmanitost-slepysu.html|access-date=2021-03-24|website=ziva.avcr.cz}}</ref><ref>{{cite journal |last1=Václav Gvozˇ dík, David Jandzik, Petros Lymberakis, Daniel Jablonski, Jirˇ í Moravec |title=Slow worm, Anguis fragilis (Reptilia: Anguidae) as a species complex: Geneticstructure reveals deep divergences |journal=Molecular Phylogenetics and Evolution |date=2010 |volume=55 |issue=2 |pages=460–472 |doi=10.1016/j.ympev.2010.01.007 |pmid=20079858 |bibcode=2010MolPE..55..460G |url=https://www.academia.edu/5309027 |access-date=1 April 2022}}</ref>

* '''''Anguis fragilis'' ''sensu stricto''''' (found in western Europe, northern Europe, and western Balkans)
* '''''[[Anguis colchica]]''''' (found in eastern and northern Europe, eastern Balkans, and in western Asia)
Three more species were later distinguished from ''A. fragilis'':
* '''''[[Anguis graeca]]''''' (found in southern Balkans)
* '''''[[Anguis veronensis]]''''' (found on the Apennine Peninsula)
*'''''[[Peloponnese slowworm|Anguis cephalonica]]''''' (native to the Peloponnese Peninsula)

== Physical traits ==
[[File:Blindschleiche Anguis fragilis.jpg|left|thumb|Slow worm in Germany]]
Slow worms have an elongated body with a circular cross-section without limbs and reach a maximum length of up to 57.5&nbsp;cm.<ref>[[Wolfgang Böhme (zoologist)|Wolfgang Böhme]]: ''A record-sized specimen of the western slow worm (Anguis fragilis).'' In: ''Zeitschrift für Feldherpetologie.'' Bd. 19, Nr. 1, 2012, {{ISSN|0946-7998}}, S. 117–118.</ref> Most adult animals are between 40 and 45&nbsp;cm long, with up to 22&nbsp;cm on the head and trunk section and the rest on the tail.<ref name="Glandt2015">Dieter Glandt: ''Die Amphibien und Reptilien Europas. Alle Arten im Porträt.'' Quelle & Meyer Verlag, Wiebelsheim 2015, {{ISBN|978-3-494-01581-1}}, S. 322–327.</ref> There is no visible neck. The tail, which ends in a horny tip, is continuous with the trunk and is often slightly longer. Slow worms exhibit [[caudal autotomy]], the severing of the tail when it is pulled by predators.<ref>{{cite journal| title=Tail regeneration in the lizards ''Anguis fragilis'' and ''Lacerta dugesii''| date=1967| last1=Bryant| first1=Susan V.| last2=Bellairs| first2=A. d'A.| journal=Zoological Journal of the Linnean Society of London| volume=46| issue=310| pages=297–305| doi=10.1111/j.1096-3642.1967.tb00510.x| url=https://www.lacerta.de/AF/Bibliografie/BIB_623.pdf}}</ref> When regrown, the tail grows back only to a short stub, probably because loss of the tail does not sufficiently affect the species' locomotion, foraging, and defence abilities to necessitate full and rapid regeneration.<ref>{{cite journal| date=2021| last1=Barr| first1=J. I.| last2=Boisvert| first2=C. A.| last3=Bateman| first3=P. W.| title=At what cost? Trade-offs and influences on energetic investment in tail regeneration in lizards following autotomy| journal=Journal of Developmental Biology| volume=9| issue=4| page=53| doi=10.3390/jdb9040053| doi-access=free| pmid=34940500| pmc=8709428}}</ref>

The skin surface consists of smooth, round to hexagonal scales that do not overlap and are of approximately the same shape on the dorsal and ventral sides of the body. There are several longitudinal rows running along the underside. In total, the trunk has 125 to 150 transverse scale rows and the tail has another 130 to 160 rows. Beneath the scales are bony plates ([[osteoderm]]s), causing slow worms to crawl much more stiffly and clumsily than snakes. The scales on the head are similar to those of snakes. The ear openings are usually completely hidden under the scales. The relatively small eyes have movable, closable eyelids (these are fused in snakes) and round pupils. The rather short tongue is broad, bilobed, and does not end in fine points. To lick, i.e. to absorb odorous substances, slow worms have to open their mouths slightly, as they lack the gap in the upper lip that snakes possess. The pointed, sometimes loosely fixed teeth are curved backwards; there are 7 to 9 teeth in the premaxilla, 10 to 12 in the maxilla, and 14 to 16 in the lower jaw.<ref name="Günther&Völkl1996">Rainer Günther, Wolfgang Völkl: ''Blindschleiche – Anguis fragilis Linnaeus, 1758.'' In: Rainer Günther (Hrsg.): ''Die Amphibien und Reptilien Deutschlands.'' Gustav Fischer, Jena u. a. 1996, {{ISBN|3-437-35016-1}}, S. 617–631.</ref>

===Size and longevity===
Adult slow worms grow to a length of approximately 50&nbsp;cm (20"), and are known for their exceptionally long lives; the slow worm may be the longest-living lizard, living about 30 years in the wild and up to at least 54 years in captivity (this record is held by a male slow worm that lived at the [[Copenhagen Zoo]] from 1892 until 1946, the age when first obtained is unknown).<ref>{{cite web |last=Smith |first=Malcolm |date=1951 |title=The British Amphibians and Reptiles |url=http://www.newnaturalists.com/product/9780007308156/The+British+Amphibians+and+Reptiles |url-status=dead |archive-url=https://web.archive.org/web/20170916052705/http://www.newnaturalists.com/product/9780007308156/The+British+Amphibians+and+Reptiles |archive-date=2017-09-16}}</ref><ref>{{cite web |title=Slow Worm |url=http://www.fourmilab.ch/images/animal_magnetism/notasnake.html}}</ref> The female often has a stripe along the spine and dark sides, while the male may have blue spots dorsally. Juveniles of both sexes are gold with dark brown bellies and sides with a dark stripe along the spine.[[File:20130505-slow worms-014-wiki©CD.jpg|thumb|Close-up of the head of a slow worm]]

== Reproduction ==
[[File:Blindschleiche 04.jpg|left|thumb|Juvenile slow worm, paperclip for size comparison]]
In Central Europe, the mating season of the species is usually between late April and June. The males often fight violently for the females, although in most populations they are in the majority. The opponents try to push each other to the ground, bite each other, and wrap themselves tightly around each other. During mating, the female is often bitten on the head or the neck, while the male inserts his two [[Hemipenis|hemipenes]] into the female's cloaca. Copulation may take several hours. 
[[File:Evening_mating_of_slow_worms_(Anguis_fragilis).jpg|thumb|Evening mating of slow worms (Anguis fragilis)]]
Females sometimes mate later with other males. The gestation period of the females is 11 to 14 weeks, after which they usually give birth to eight to twelve young (extreme values: 2 to 28) between mid-July and the end of August, sometimes even later. Slow worms are [[Ovoviviparity|ovoviviparous]]; at birth, the 7 to 10&nbsp;cm long young animals are in a very thin, transparent egg shell, which they pierce immediately afterwards. They initially weigh less than a gram and still have a remnant of the yolk.<ref name="Wolfbeck&Fritz2007">Heribert Wolfbeck, Klemens Fritz: ''Blindschleiche, Anguis fragilis Linnaeus, 1758.'' In: Hubert Laufer, Klemens Fritz, Peter Sowig: ''Die Amphibien und Reptilien Baden-Württembergs.'' Ulmer, Stuttgart 2007, {{ISBN|978-3-8001-4385-6}}, S. 619–632.</ref> Juvenile slow worms have a contrasting color scheme and pattern. The upper side of the body is silvery white to golden yellow, while the sides and underside are black.

== Predators ==
Predators of ''A. fragilis'' include [[Vipera berus|adders]], [[European badger|badgers]], [[Bird of prey|birds of prey]], [[Corvus|crows]], [[Cat|domestic cats]], [[Red fox|foxes]], [[Hedgehog|hedgehogs]], [[Common pheasant|pheasants]], and [[Smooth snake|smooth snakes]].<ref>{{Cite web |last=Ornithology |first=British Trust for |date=2010-11-24 |title=Slow-worm |url=https://www.bto.org/our-science/projects/gbw/gardens-wildlife/garden-reptiles-amphibians/a-z-reptiles-amphibians/slow-worm |access-date=2022-09-10 |website=BTO - British Trust for Ornithology |language=en}}</ref><ref>{{Cite web |title=Slow Worm |url=http://surrey-arg.org.uk/SARGWEB.php?app=SpeciesData&Species=slow_worm |access-date=2022-09-10 |website=surrey-arg.org.uk}}</ref><ref>{{Cite web |title=Slow-Worm |url=https://www.froglife.org/info-advice/amphibians-and-reptiles/slow-worm/ |access-date=2022-09-10 |website=www.froglife.org}}</ref><ref>{{Cite web |title=Smooth snake {{!}} The Wildlife Trusts |url=https://www.wildlifetrusts.org/wildlife-explorer/reptiles/smooth-snake |access-date=2022-09-10 |website=www.wildlifetrusts.org |language=en}}</ref> Slow worms detect the presence of predators with their tongues by flicking them in and out to 'smell'.<ref>{{Cite web |title=Slow worms: Britain's most unusual lizards |url=https://www.nhm.ac.uk/discover/slow-worms-most-unusual-lizards-in-britain.html |access-date=2024-03-19 |website=www.nhm.ac.uk |language=en}}</ref>

== Ecology ==
These reptiles are largely nocturnal and do not bask in the sun like other reptiles, instead choosing to warm themselves indirectly under objects such as rocks that have been warmed by the sun. They are often found in long [[grass]] and other moist environments.<ref>{{cite web |last1=Grace Bettayeb |title=Species in Focus: Slow Worm |url=https://iwt.ie/species-in-focus-slow-worm/ |access-date=1 April 2022 |website=iwt.ie |date=16 March 2022 |publisher=Irish Wildlife Trust}}</ref> In a 2009 study of a Danish population, the diet of the slow worm was found to include [[Slug|slugs]], [[Snail|snails]], [[Earthworm|earthworms]], [[Caterpillar|caterpillars]], and [[Pill millipede|pill millipedes]].<ref>{{Cite journal |last1=Pedersen |first1=Iben Lindegaard |last2=Jensen |first2=Jan Kjærgaard |last3=Toft |first3=Søren |date=2009-04-01 |title=A method of obtaining dietary data for slow worms (Anguis fragilis) by means of non-harmful cooling and results from a Danish population |url=https://doi.org/10.1080/00222930802702464 |journal=Journal of Natural History |volume=43 |issue=15–16 |pages=1011–1025 |doi=10.1080/00222930802702464 |bibcode=2009JNatH..43.1011P |s2cid=84703263 |issn=0022-2933|url-access=subscription }}</ref>

==Protected status in the UK==
In the United Kingdom, the slow worm has been granted [[Conservation status|protected status]], alongside all other native [[British reptile species]]. The slow worm population has been declining, and under the [[Wildlife and Countryside Act 1981]], to intentionally kill, injure, sell, or advertise to sell them is illegal.<ref name="Wildlife">{{cite web |title=Slow worm {{!}} The Wildlife Trusts |url=https://www.wildlifetrusts.org/wildlife-explorer/reptiles/slow-worm |access-date=26 July 2022 |website=www.wildlifetrusts.org}}</ref><ref>{{cite web|url=http://www.bbc.co.uk/nature/wildfacts/factfiles/281.shtml| title=BBC - Science & Nature - Wildfacts - Slow worm | publisher=BBC |access-date=2007-05-16| archive-url= https://web.archive.org/web/20070504002435/http://www.bbc.co.uk/nature/wildfacts/factfiles/281.shtml| archive-date= 4 May 2007 }}</ref><ref>{{cite web |url=http://www.legislation.gov.uk/ukpga/1981/69 |title=Wildlife and Countryside Act 1981 |publisher=Legislation.gov.uk |access-date=20 September 2015 }}</ref>

==Ireland==
The slow worm is assumed to be non-native in Ireland, possibly arriving in the 1900s. Due to their secretive habits they are difficult to observe and are sighted only in parts of [[County Clare]] and possibly [[County Galway]], mainly in [[the Burren]] region.<ref>{{cite web |last1=Grace Bettayeb |title=Species in Focus: Slow Worm |url=https://iwt.ie/species-in-focus-slow-worm/ |website=iwt.ie |date=16 March 2022 |publisher=Irish Wildlife Trust |access-date=1 April 2022}}</ref><ref>{{cite web|url=http://www.npws.ie/media/npwsie/content/images/protectedsites/sitesynopsis/SY001926.pdf |title=Archived copy |access-date=2014-01-25 |url-status=dead |archive-url=https://web.archive.org/web/20140203030313/http://www.npws.ie/media/npwsie/content/images/protectedsites/sitesynopsis/SY001926.pdf |archive-date=2014-02-03 }}</ref><ref>{{cite web |last1=Dick Warner |title=Slow worm makes its entrance |url=https://www.irishexaminer.com/opinion/columnists/arid-20225783.html |website=irishexaminer.com |date=18 March 2013 |publisher=Irish Examiner |access-date=31 March 2022}}</ref>

== Evolutionary history ==
Members of the genus ''[[Anguis]]'', to which the slow worm belongs, first appeared in Europe during the [[Mammal Paleogene zone]] 14, between 43.5 and 41.2 million years ago, corresponding to the [[Lutetian]] stage of the [[Eocene]].<ref>{{Cite journal|last=Rage|first=Jean-Claude|date=December 2012|title=Amphibians and squamates in the Eocene of Europe: what do they tell us?|url=http://link.springer.com/10.1007/s12549-012-0087-3|journal=Palaeobiodiversity and Palaeoenvironments|language=en|volume=92|issue=4|pages=445–457|doi=10.1007/s12549-012-0087-3|bibcode=2012PdPe...92..445R |s2cid=128651937|issn=1867-1594|url-access=subscription}}</ref> Remains assigned to the ''Anguis fragilis'' [[species complex]] are known from the late [[Miocene]] onwards.<ref>{{Cite journal|last1=Villa|first1=Andrea|last2=Delfino|first2=Massimo|date=November 2019|title=Fossil lizards and worm lizards (Reptilia, Squamata) from the Neogene and Quaternary of Europe: an overview|journal=[[Swiss Journal of Palaeontology]]|language=en|volume=138|issue=2|pages=177–211|doi=10.1007/s13358-018-0172-y|issn=1664-2384|doi-access=free|bibcode=2019SwJP..138..177V }}</ref>

==Gallery==
<gallery widths="200" heights="160">
File:Common slowworm (Anguis fragilis).jpg|A slow worm
File:Slow-worm-close.jpg|A slow worm close
File:Padalec turkusowy, Beskid Sądecki.jpg|Slow worm in turquoise color
File:Blindschleich77.jpg
File:Slow worm in grass.ogv|A slow worm moving through grass. This individual is a juvenile, as evinced by its golden colouration.
File:Blindschleiche sucht Schutz.webm|A slow worm seeks protection.
</gallery>

==See also==
* [[Glass lizard|Glass snake]]
* [[Pygopodidae]]
* [[limbless vertebrate]] 

==References==
{{Reflist}}

== External links ==
* {{Commons-inline}}

{{Taxonbar|from=Q183660}}
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{{DEFAULTSORT:Anguis Fragilis}}
[[Category:Anguis]]
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[[Category:Lizards of Asia]]
[[Category:Lizards of Europe]]
[[Category:Reptiles described in 1758]]
[[Category:Taxa named by Carl Linnaeus]]