At a glance
Essentials
- Size
- Adults measure between 30 and 40 cm, with females that can reach 50 cm. Juveniles are born with about 10 cm. The range may vary with age, sex and population.
- Distribution
- Native to Europe and eastern Asia. In the Iberian Peninsula, it occupies the northern half, with an isolated southern population south of the Tagus River in Portugal.
- Habitat
- Wet meadows, deciduous forests, shrublands, and areas with dense herbaceous vegetation. In the Iberian Peninsula, it is found in the northern half, especially on the Cantabrian coast, Galicia, northern Aragon, Catalonia, and northern Portugal, absent in much of the northern submeseta and the Ebro valley.
- Activity
- Sedentary and semisubterranean. Active in early light hours, twilight, and after rains. Hibernates from October/November to March/April.
- Diet
- It feeds mainly on invertebrates such as snails, slugs, and earthworms.
- Conservation
- Least Concern (LC) according to the IUCN at the global level.
Observation guide
What to look for
- 01
It has mobile eyelids and small eyes, unlike snakes which have their eyes covered by a transparent and fixed scale.
- 02
It practices caudal autotomy: it severs its tail when grabbed by a predator, and the regenerated tail is shorter and stiffer.
- 03
Its skin is smooth, with scales that do not overlap, and it has osteoderms (bony plates) under the skin that give it rigidity.
- 04
Juveniles are golden in color with a dark dorsal stripe, while adults vary, with males possibly having blue spots.
Lighting, age and viewing angle can hide features. If identification affects consumption, handling or conservation, consult specialist sources.
Ecology
Description and characteristics
The slow worm is a legless lizard (without limbs) of the family Anguidae. Although its appearance resembles that of a snake, it possesses distinct anatomical features, such as mobile eyelids and a forked tongue that does not end in fine tips, unlike snakes. Its skin is smooth and glossy, covered by rounded or hexagonal scales that do not overlap, and beneath these are bony plates (osteoderms) that give it a characteristic rigidity in its movements.
Adults generally measure between 30 and 40 cm, although females can reach up to 50 cm. The tail, which is continuous with the trunk and ends in a horny tip, represents a significant part of the total length. When grabbed by the tail, the slow worm practices caudal autotomy, severing its tail to escape from predators; the regenerated tail is shorter, stiffer, and darker in color than the original.
It is a semisubterranean and sedentary species that spends much of its time hidden under objects, dense vegetation, or in the ground. Its activity is irregular and influenced by the environment, being more active during the first hours of light, at dusk, and after rains. In winter, it enters a state of torpor (hibernation) that can last from October or November until late March or early spring, often in underground shelters where it can hibernate in groups of up to 100 individuals.
Regarding its reproduction, the slow worm is ovoviviparous: the female retains the eggs inside her body until they hatch, giving birth to fully formed young. Gestation lasts between three and five months, and the litter usually consists of between 6 and 24 young, which are born with a length of approximately 10 cm. Juveniles of both sexes have a golden color with a dark stripe along the back, while adults vary in coloration, with males that may present blue spots on the back.