Slow worm

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Slow worm
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Anguidae
Genus: Anguis
A. fragilis
Binomial name
Anguis fragilis

The slow worm (Anguis fragilis) is a reptile native to western Eurasia. It is also called a deaf adder, a slowworm,[2][3] a blindworm, or regionally, a long-cripple. These legless lizards are also sometimes called common slowworms. The "blind" in blindworm refers to the lizard's small eyes, similar to a blindsnake (although the slowworm's eyes are functional).

Slow worms are semifossorial[4] (burrowing) lizards, spending much of their time hiding underneath objects. The skin of slow worms is smooth with scales that do not overlap one another. Like many other lizards, they 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, they are common in gardens, and can be encouraged to enter and help remove pest insects by placing black plastic or a piece of tin on the ground. On warm days, one or more slow worms can often be found underneath these heat collectors. One of the biggest causes of mortality in slow worms in suburban areas is the domestic cat, against which it has no defense.

Slow worms have been shown to be a species complex, consisting of 5 distinct but similar species.


Distribution of species of European slow worms

Anguis fragilis was traditionally divided into two subspecies (A. f. fragilis and A. f. colchica), but they are now classified as separate species:[5]

  • Anguis fragilis sensu stricto (found in western Europe, northern Europe and western Balkans) and
  • Anguis colchica (found in eastern Europe, eastern Balkans and in western Asia).

Three more species were later distinguished from A. fragilis:

  • Anguis graeca (found in southern Balkans) and
  • Anguis veronensis (found on the Apennine Peninsula).
  • Anguis cephalonica (native to the Peloponnese Peninsula)

Physical traits[edit]

Close-up of the head of a slow worm

These reptiles are mostly active during the twilight and occasionally bask in the sun, but are more often found hiding beneath rocks and logs. They are carnivorous and, because they feed on slugs and worms, they can often be found in long grass and other damp environments.

The females give birth to live young (ovoviviparous birth). In the days leading up to birth, the female can often be seen basking in the sun on a warm road.

Although these lizards are often mistaken for snakes, a number of features differentiate them. The most important one is that they have small eyes with eyelids that, like other lizards, blink. Unlike snakes, they may also have visible ears. They shed their skin in patches, whereas most snakes shed their skins whole. Slow worms may also shed their tails (autotomy) as a defense mechanism, by breaking one of their tail vertebrae in half. The pattern of a slow worm's ventral scales is also different from that of a snake's.

Size and longevity[edit]

Adult slow worms grow to be about 50 cm (20") long, 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).[6][7] 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.

Protected status in the UK[edit]

In the United Kingdom, the slow worm has been granted protected status, alongside all other native British reptile species. The slow worm has been decreasing in numbers, and under the Wildlife and Countryside Act 1981, to intentionally kill, injure, sell, or advertise to sell them is illegal.[8][9]


The slow worm is not native to Ireland, but is believed to have been illegally introduced in the 1970s. It has been sighted only in parts of County Clare, mainly in the Burren region.[10][11][12]

Evolutionary history[edit]

Members of the genus Anguis, to which the slow worm belongs, first appeared during Europe during Mammal Paleogene zone 14, between 43.5 and 41.2 million years ago, corresponding to the Lutetian stage of the Eocene.[13] Remains assigned to the Anguis fragilis species complex are known from the late Miocene onwards.[14]


Distribution of species of European slow worms

It was traditionally divided into four subspecies, but newly they are classified as separate species:[5]

  • Anguis fragilis sensu stricto (found in western Europe, northern Europe and western Balkans),
  • Anguis colchica (found in eastern Europe, eastern Balkans and in western Asia),
  • Anguis graeca (found in southern Balkans) and
  • Anguis veronensis (found on the Apennine Peninsula).


See also[edit]


  1. ^
  2. ^ The "slow-" in slowworm is distinct from the English adjective slow ("not fast"); the word comes from Old English slāwyrm, where slā- means 'earthworm' or 'slowworm' and wyrm means "serpent, reptile". ("Slowworm". The American Heritage Dictionary of the English Language. Houghton Mifflin Harcourt. 2017.)
  3. ^ "Anguis fragilis". The Reptile Database. Retrieved 2021-04-07.
  4. ^ "Feeding state and selected body temperatures in the slow worm" (PDF). Herpetological Journal. 18: 59–62. 2008. Archived from the original (PDF) on 17 June 2009. Retrieved 2009-06-03.
  5. ^ a b "Živa – Přehlížená rozmanitost slepýšů (Jiří Moravec, Václav Gvoždík)". Retrieved 2021-03-24.
  6. ^ Smith, Malcolm (1951). "The British Amphibians and Reptiles". Archived from the original on 2017-09-16.
  7. ^ "Slow Worm".
  8. ^ "BBC - Science & Nature - Wildfacts - Slow worm". BBC. Archived from the original on 4 May 2007. Retrieved 2007-05-16.
  9. ^ "Wildlife and Countryside Act 1981". Retrieved 20 September 2015.
  10. ^ Irish Wildlife Trust Lizard Survey
  11. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2014-02-03. Retrieved 2014-01-25.CS1 maint: archived copy as title (link)
  12. ^ Slowworm makes its entrance, by Dick Warner. Irish Examiner, March 18, 2013
  13. ^ Rage, Jean-Claude (December 2012). "Amphibians and squamates in the Eocene of Europe: what do they tell us?". Palaeobiodiversity and Palaeoenvironments. 92 (4): 445–457. doi:10.1007/s12549-012-0087-3. ISSN 1867-1594.
  14. ^ Villa, Andrea; Delfino, Massimo (November 2019). "Fossil lizards and worm lizards (Reptilia, Squamata) from the Neogene and Quaternary of Europe: an overview". Swiss Journal of Palaeontology. 138 (2): 177–211. doi:10.1007/s13358-018-0172-y. ISSN 1664-2384.

External links[edit]