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 blind-worm 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 the entire species complexAnguis is also called "slow-worms".
Common slow worms are semifossorial[2] (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 allotments, and can be encouraged to enter and help remove pest insects by placing black plastic or providing places to shelter such as piles of logs, corrugated iron sheets or under tiles.[3] On warm days, one or more slow worms can often be found underneath these heat collectors.
The name "slowworm" is only contaminated by the word "slow". In Middle English, it was written "slowurm", from Old English "slāwyrm", where slā- means 'earthworm' or 'slowworm' and wyrm means "serpent, reptile".[4][5] It is related to the Norwegian slo or Swedish ormslå, of same meaning.
Taxonomy
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:[6][7]
Anguis fragilissensu stricto (found in western Europe, northern Europe and western Balkans) and
Anguis colchica (found in eastern and northern Europe, eastern Balkans and in western Asia).
Three more species were later distinguished from A. fragilis:
Slow worms have an elongated body with a circular cross-section without limbs and reach a maximum length of up to 57.5cm.[8] Most adult animals are between 40 and 45cm long, with up to 22cm on the head and trunk section and the rest on the tail.[9] 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.[10] 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.[11]
The skin surface consists of smooth, round-to-hexagonal scales which do not overlap over one another and are roughly the same shape on the dorsal and ventral surfaces 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. Under the scales there are bony plates (osteoderms), so that slow worms crawl much more stiffly and clumsily than snakes. The scaling of the head is similar to that of snakes. The ear openings are mostly 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 tips. 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.[12]
Size and longevity
Adult slow worms grow to be about 50cm (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).[13][14] 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.
Close-up of the head of a slow worm
Reproduction
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 wrestle violently around the females, although they are in the majority in most populations. The opponents try to push each other to the ground, bite each other and wrap themselves tightly around each other. When mating, the female is bitten in the head or neck region, while the male introduces his two hemipenes into the female's cloaca. Copulation can take several hours.
Evening mating of slow worms (Anguis fragilis)
Sometimes, females mate with other males later. The gestation period of the females lasts 11 to 14 weeks, and subsequently, between mid-July and the end of August, and sometimes even later, they usually give birth to between eight and twelve young (extreme values: 2 to 28). Slow worms are ovoviviparous; at birth, the 7 to 10cm 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.[15] Juvenile slow worms have a contrasting color scheme and pattern. The top of the body is silvery-white to golden yellow, while the sides and underside are black.
These reptiles are largely nocturnal and do not bask in the sun like other reptiles, but choose to warm themselves indirectly underneath objects, such as rocks, which have been warmed by the sun. They can often be found in long grass and other damp environments[21] In a 2009 study of a Danish population, the diet of the slow-worm was found to include slugs, snails, earthworms, caterpillars and pill millipedes.[22]
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.[26][27][28]
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.[29] Remains assigned to the Anguis fragilisspecies complex are known from the late Miocene onwards.[30]
Gallery
A slow worm
A slow worm close
Slow worm in turquoise color
A slow worm moving through grass. This individual is a juvenile, as evinced by its golden colouration.
Anguidae refers to a large and diverse family of lizards native to the Northern Hemisphere. Common characteristics of this group include a reduced supratemporal arch, striations on the medial faces of tooth crowns, osteoderms, and a lateral fold in the skin of most taxa. The group is divided into two living subfamilies, the legless Anguinae, which contains slow worms and glass lizards, among others, found across the Northern Hemisphere, and Gerrhonotinae, which contains the alligator lizards, native to North and Central America. The family Diploglossidae was also formerly included. The family contains about 87 species in 8 genera.
Slowworms are a small genus (Anguis) of snake-like legless lizards in the family Anguidae. The genus has several living species, including the common slowworm, the eastern slowworm, the Greek slowworm, the Peloponnese slowworm, and the Italian slowworm. There are also known fossil species.
The Tiliqua scincoides scincoides, or eastern blue-tongued lizard, is native to Australia. Its blue tongue can be used to warn off predators. In addition to flashing its blue tongue, the skink hisses and puffs up its chest to assert dominance and appear bigger when in the presence of its predators such as large snakes and birds. The eastern blue tongue is ovoviviparous and precocial, meaning that its young are more developed and advanced at their time of birth. The Tiliqua scincoides scincoides is not venomous to humans and can be found in suburban and urban areas, specifically in house gardens.
Vipera aspis is a viper species found in southwestern Europe. Its common names include asp, asp viper, European asp, and aspic viper, among others. Like all other vipers, it is venomous. Bites from this species can be more severe than from the European adder, V. berus; not only can they be very painful, but approximately 4% of all untreated bites are fatal. The specific epithet, aspis, is a Greek word that means "viper." Five subspecies are currently recognized, including the nominate subspecies described here.
Langford Heathfield is a 95.4 hectare biological Site of Special Scientific Interest at Langford Budville, 3 km (1.9 mi) north west of Wellington in Somerset, notified in 1966.
The eastern glass lizard is a species of legless lizard in the family Anguidae and the longest and heaviest species of glass lizards in the genus Ophisaurus, endemic to the Southeastern United States. The streamlined, legless species is often confused with snakes. Glass lizards differ from snakes as they possess a moveable eyelid and an external ear opening as well as a lateral groove that separates the different types of scales on the animal, all three of these features are absent in snakes. Snakes also have flexible jaws while lizards do not. Ventralis comes from the Latin "venter" meaning belly; this is in reference to the snake-like movement.
In the 10th edition of Systema Naturae, Carl Linnaeus described the Amphibia as:
Animals that are distinguished by a body cold and generally naked; stern and expressive countenance; harsh voice; mostly lurid color; filthy odor; a few are furnished with a horrid poison; all have cartilaginous bones, slow circulation, exquisite sight and hearing, large pulmonary vessels, lobate liver, oblong thick stomach, and cystic, hepatic, and pancreatic ducts: they are deficient in diaphragm, do not transpire (sweat), can live a long time without food, are tenatious of life, and have the power of reproducing parts which have been destroyed or lost; some undergo a metamorphosis; some cast (shed) their skin; some appear to live promiscuously on land or in the water, and some are torpid during the winter.
Anguis veronensis, commonly known as the Italian slow worm, is a European lizard species in the family Anguidae. The slow worm is distributed throughout Italy and in southeastern part of France.
Anguis colchica, the eastern slow worm, is a species of legless lizard in the family Anguidae found in eastern and northern Europe and Asia. It is easily confused with the common slow worm, due to their physical similarities, and the proximity of their distribution.
↑ Wolfgang Böhme: A record-sized specimen of the western slow worm (Anguis fragilis). In: Zeitschrift für Feldherpetologie. Bd. 19, Nr. 1, 2012, ISSN0946-7998, S. 117–118.
↑ Dieter Glandt: Die Amphibien und Reptilien Europas. Alle Arten im Porträt. Quelle & Meyer Verlag, Wiebelsheim 2015, ISBN978-3-494-01581-1, S. 322–327.
↑ Rainer Günther, Wolfgang Völkl: Blindschleiche – Anguis fragilis Linnaeus, 1758. In: Rainer Günther (Hrsg.): Die Amphibien und Reptilien Deutschlands. Gustav Fischer, Jena u. a. 1996, ISBN3-437-35016-1, S. 617–631.
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