Common slow worm

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 not a worm or a snake.

Common slow worms are semifossorial (burrowing) lizards that spend much of their time hiding underneath objects. They have smooth skin with scales that do not overlap. These interesting creatures play an important role in their habitats, helping to control insect populations.

Etymology

The name "blindworm" comes from the lizard's small eyes, which look similar to those of a blindsnake, even though the slow worm's eyes still work. People often just call this lizard a "slow worm," but all lizards in the genus Anguis are called "slow worms."

The word "slow worm" might seem confusing because it has the word "slow" in it. Long ago, in Middle English, it was written "slowurm," coming from Old English words meaning "earthworm" or "slow worm." This name is related to words in Norwegian and Swedish that mean the same thing.

Taxonomy

The common slow worm, Anguis fragilis, used to be split into two groups called subspecies. But now scientists say these are really two different species:

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

Later, three more species were identified:

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

Physical traits

Slow worms are legless lizards with long, slender bodies. They can grow up to about 57.5 centimeters long, but most adults are around 40 to 45 centimeters. They don’t have a visible neck, and their tails look the same as their bodies. If a slow worm loses its tail, it will grow back smaller.

Their skin is made of smooth, overlapping scales, and they have small eyes with movable eyelids. Unlike snakes, they have ears covered by scales and a broad, forked tongue. Slow worms have special bony plates under their scales that make them move more slowly than snakes.

Size and longevity

Adult slow worms are about 50 centimeters long and can live a very long time. In the wild, they may live up to 30 years, and in captivity, they can live even longer — up to at least 54 years. One slow worm lived at the Copenhagen Zoo from 1892 until 1946.

Reproduction

In Central Europe, the mating season for the common slow worm is usually from late April to June. Males sometimes fight for the chance to mate with females. After mating, the female carries her babies for 11 to 14 weeks. She gives birth to between eight and twelve babies, though sometimes there can be as few as two or as many as twenty-eight. The babies are born inside a thin, clear shell that they break out of right away. When they are born, they are about 7 to 10 centimeters long and weigh less than a gram.

Ecology

Slow worms warm themselves by hiding under objects like rocks that the sun has heated. You can often find them in gardens and places with long grass. They help by eating pests like insects.

Slow worms are eaten by animals such as adders, badgers, birds of prey, crows, domestic cats, foxes, hedgehogs, pheasants, and smooth snakes. They can drop their tails to escape danger, and the tail grows back but is shorter than before. They eat insects, snails, and earthworms.

Protected status in the UK

In the United Kingdom, the common slow worm has been given special protection, just like all the other native British reptiles. The number of slow worms has been going down, so under a law from 1981, it is against the law to hurt, sell, or try to sell them on purpose.

Biogeography

The slow worm might not be originally from Ireland, possibly arriving there in the 1900s. Because they are quiet and hard to see, they are only spotted in parts of County Clare and maybe County Galway, mostly in the the Burren region.

Evolutionary history

The common slow worm belongs to a group of animals called Anguis. These animals first appeared in Europe a very long time ago, during a time called the Mammal Paleogene zone, between 43.5 and 41.2 million years ago. This was during a part of history known as the Lutetian stage of the Eocene epoch. Scientists have found fossils of these creatures from even later times, called the late Miocene period.