Slow worm

The Slow Worm: A Legless Lizard of Europe

The common slow worm, scientifically known as Anguis fragilis, is a non-venomous species of legless lizard native to Europe. Despite common misconceptions, it is not a snake or a true worm, but rather a reptile with a distinctive elongated body and smooth, non-overlapping scales. This species is also recognized by various other common names, including deaf adder, blindworm, long-cripple, steelworm, and hazelworm.

Physical Characteristics and Habitat

Slow worms typically reach lengths of up to 57.5 cm, with most adults measuring between 40 and 45 cm. They lack visible necks, and their tails, which end in a horny tip, are often slightly longer than their head and trunk section. A notable defense mechanism is caudal autotomy, the ability to shed their tail when threatened by predators, though the regrown tail is usually a short stub. Their skin is covered in smooth, round to hexagonal scales, beneath which lie bony plates (osteoderms) that contribute to a more rigid movement compared to snakes. The eyes are relatively small but possess movable eyelids and round pupils, and their tongue is broad and bilobed.

These reptiles are semifossorial, meaning they spend a significant portion of their lives burrowing or hiding under objects such as rocks, logs, or debris in moist environments. They are often found in long grass, gardens, and allotments. Instead of basking directly in the sun, slow worms tend to warm themselves indirectly using surfaces that have been heated by the sun. Their activity patterns are often dictated by environmental conditions, with peak activity occurring during the early hours of sunlight, twilight, and after rainfall, which may correlate with the activity of their prey.

Diet, Reproduction, and Lifespan

The diet of the slow worm primarily consists of invertebrates, with slugs, snails, and earthworms being common food sources. They are ovoviviparous, a reproductive strategy where the eggs hatch inside the mother, and live young are born enveloped in a thin, transparent eggshell, which they quickly break free from. Gestation typically lasts between 11 and 14 weeks, resulting in litters of eight to twelve offspring, though extreme numbers have been recorded. Juveniles are born at 7 to 10 cm in length and weigh less than a gram. Slow worms are renowned for their exceptionally long lifespans, with individuals living around 30 years in the wild and potentially exceeding 54 years in captivity, making them one of the longest-living lizard species known.

Conservation and Distribution

While the slow worm is found across Europe and into parts of Western Asia, its population in the United Kingdom has been declining, leading to protected status under the Wildlife and Countryside Act 1981. This legislation makes it illegal to intentionally kill, injure, or trade them. The species is also considered non-native in Ireland, with sightings primarily reported in County Clare.