Slow Worm

Quick Take

• This legless reptile looks exactly like a snake, though one tiny detail gives it away every time. See the distinguishing features →
• Slow worms outlive nearly every other lizard on Earth, and the margin by which they do so would surprise most people. Discover their lifespan →
• When cornered by a predator, slow worms deploy an escape trick far stranger than just running away. Explore their defense tactics →
• Gardeners who spot one in their yard are luckier than they realize, and there is a good reason for that. See why gardeners benefit →

The slow worm is a grayish-brown lizard, even though it is often mistaken for a snake. Despite their forked yet flat tongue, their eyelids are a giveaway that these reptiles are lizards. To escape predators, they smooth their movement by lowering their tails as they move away.

While female slow worms are brown with dark sides, the males are grayish-brown. They are no threat to humans, as they do not bite and only measure about 19.7 inches (50 cm) long. With a long stripe down their body, black bellies, and gold or silver dorsal sides, these slim reptiles are rather distinguished.

5 Incredible Slow Worm Facts

• The heads of slow worms are small, matching their slim 20-inch body.
• Though they look strikingly close to snakes, this reptile species distinguishes itself with eyelids and ear openings.
• Slow worms are diurnal, meaning they are active predominantly during the day.
• Slow worms can live up to 20 to 30 years in the wild, with at least one individual recorded surviving for over 50 years in captivity.
• Slow worms can also detach their tails while escaping predators, though they can grow them back.

Classification and Scientific Name

Slow worms, also known as the deaf adder, go by the scientific name Anguis fragilis. They belong to the kingdom Animalia and phylum Chordata. The class is Reptilia, and the order is Squamata. Their family is called Anguidae, and the genus is called Anguis.

The first word of their scientific name, “Anguis”, is rooted in the Proto-Indo-European word for “snake,” even though they are considered to be a lizard. “Fragilis,” on the other hand, comes from the Latin word “fragilis,” meaning “fragile” or “breakable” — the same root from which the French word ‘frêle,’ meaning “weak” or “frail,” is derived — perhaps as a reference to their slim body.

Appearance

The slow worm, or the deaf adder, is often mistaken for a snake for its long body and lack of legs. However, they are simply a lizard that needs a little further inspection to see the difference. To start, these legless reptiles are smooth and glossy, complementing their cylindrical shape. They also have thin eyelids and small ear holes, which snakes do not.

When the slow worm is young, its body is relatively thin and only about 2.8 to 3.9 inches (7 to 10 cm) long. The bodies of the slow worms are shiny, but the males and females are slightly different. While the male slow worms are grayish-brown in color, the females are brown with dark sides.

The body of a deaf adder features a golden or silver dorsal side with a black belly. A dark stripe runs along the length of their bodies. Much like other lizards, slow worms can shed their tails while escaping predators.

Behavior

While other British reptiles enjoy basking in the sun, the slow worm does not. Instead, they prefer to hide under logs. If a compost heap is nearby, they’ll even hide there when they aren’t hunting for their next meal.

the slow worm is a diurnal reptile, which means that it is usually active during the day and rests during the night. However, they aren’t much of a threat to anyone but their prey. They do not seek out humans to bite, but they will shake the end of their tail as a distraction for predators. Once the predator is distracted, the slow worm will take the opportunity to move away. Some of these reptiles will even shed their tail or defecate to escape.

These animals thrive in their natural environment and are not suited to captivity. If humans encounter them in the wild, they have to leave them alone. The Wildlife and Countryside Act of 1981 protects these reptiles within the United Kingdom.

Though they shouldn’t be kept as pets, the reptile may end up creeping into domestic gardens. They are not at all dangerous to humans, but they can come in quite handy around the home. Since they hunt insects, they can clean up the gardens that they reside in, which is beneficial for avid gardeners who want to preserve their plant life.

Habitat

These reptiles can be found in a variety of places. They usually live in areas such as edges of woodlands like the Caledonian Forest, tussocky grasslands, allotments, gardens, heathlands, and grassy meadows. They are relatively easy to locate throughout mainland Britain, but the most common areas to find them include the south-west area of England and Wales. Interestingly, they do not reside in any part of Ireland at all, despite its proximity.

They do not like to live in captivity and prefer hiding under the earth or in compost or dung heaps. Therefore, keeping them as a pet is never a great idea. However, if you still want to keep them, it would be necessary to create conditions that mimic their natural habitat so they can thrive. They may be better off in the garden where they can roam and feed freely.

Diet

These animals are carnivores, so they eat other animals that are rather easy for them to catch. Many of the animals that they seek out are invertebrates that can be easily found in their dark habitats. Often, they will eat worms, slugs, spiders, and snails. Though they have a similar build to the snake, they cannot expand their body to make room for larger prey.

What Does the Slow Worm Eat?

These animals feed on a variety of invertebrates, including spiders, worms, slugs, and snails. They maintain a carnivorous diet and do not eat plants as other worms do.

Predators and Threats

Slow worms are small reptiles, making them a quick meal for many predators. However, one of their biggest threats has historically been humans. Due to their similarity to snakes, many people previously killed or traded them. The activity became so common that they are now a “priority species” under the UK Post-2010 Biodiversity Framework.

Currently, they are protected under the Wildlife and Countryside Act, 1981. The law makes injuring, selling, or killing the slow worm a crime.

What Eats Slow Worms?

Due to their small size, these reptiles are prone to being eaten by a lot of animals and birds. Some of the common predators of the slow worm include adders, pheasants, badgers, domestic cats, and hedgehogs.
However, like lizards, slow worms also shed their tails while escaping from predators, smoothing the process for them. Not only that, but they are also known to defecate, which produces a foul smell and wards off predators, keeping them safe.

Reproduction, Babies, and Lifespan

Mating begins with the male biting the female’s head or neck. To reproduce, the male and female slow worms will intertwine their bodies, engaging in a process that ultimately can take up to 10 hours to complete. The mating season typically starts just before summertime, and the males tend to become aggressive in their competition to find a fertile female.

These lizards are known to be viviparous, which means that they give birth to live young. the young develop inside the female’s body until birth, at which point the mother releases them.

After hatching, the young remain in the mother’s body for a while. While inside the mother’s body, the young live off the yolk of eggs that hatch internally.

Eventually, the female gives birth, and the young emerge. Babies of slow worms are usually very thin and are between 2.8 and 3.9 inches (7–10 cm) long. Most births will occur during summer, and typically between 6 and 12 young are released at that time.

Slow worms are among the longest-living lizards. While they can live 20 to 30 years in the wild, some have been recorded living for over 50 years in captivity.

Population

Found throughout many parts of Britain, the exact population of these animals is not known. Presently, the UK protects them under the Wildlife and Countryside Act, which was established in 1981. The law prevents humans from injuring, selling, or killing them.

Slow Worm In the Zoo

Presently, there are very few zoo locations that list these reptiles as one of their supported animals. However, you may be able to find them at the Yaroslavl Zoo, which is located in Russia.