蛇蜥种

The common slow worm (Anguis fragilis) is a non-venomous species of legless lizard native to Europe. It is also called a deaf adder, blindworm, or regionally, a long-cripple, steelworm, and hazelworm.

Despite its name, the common slow worm is neither a worm nor a snake.

Common slow worms are semifossorial (burrowing) lizards that spend much of their time hiding underneath objects. The skin of slow worms is smooth, with scales that do not overlap.

Etymology

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".

The name "slow worm" is only 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". It is related to the Norwegian slo or Swedish ormslå, of same meaning.

Taxonomy

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:

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)
• Anguis cephalonica (native to the Peloponnese Peninsula)

Physical traits

Slow worms have an elongated body with a circular cross-section without limbs and reach a maximum length of up to 57.5cm. 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. 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.

Reproduction

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 hemipenes into the female's cloaca. Copulation may take several hours.

Ecology

These reptiles do not bask in the sun like other species, 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. In the UK, slow worms are commonly encountered in gardens and 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. On warm days, one or more slow worms can often be found underneath these heat collectors.

Protected status in the UK

In the United Kingdom, the slow worm has been granted 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.

Biogeography

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.

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. Remains assigned to the Anguis fragilis species complex are known from the late Miocene onwards.