Slow Worm

Anguis fragilis

Last updated: February 14, 2021
Verified by: AZ Animals Staff
© Sandra Standbridge/

Found widely throughout British gardens!


Slow Worm Scientific Classification

Scientific Name
Anguis fragilis

Read our Complete Guide to Classification of Animals.

Slow Worm Conservation Status

Slow Worm Locations

Slow Worm Locations

Slow Worm Facts

Main Prey
Insects, Slugs, Worms
Fun Fact
Found widely throughout British gardens!
Distinctive Feature
Long snake-like body and small eyes
Grassland and woodlands
Cats, Dogs, Birds
  • Solitary
Favorite Food
Average Clutch Size
Found widely throughout British gardens!

Slow Worm Physical Characteristics

  • Brown
  • Grey
  • Yellow
  • Black
  • Tan
Skin Type
Top Speed
0.3 mph
10 - 30 years
20g - 100g (0.7oz - 3.5oz)
20cm - 50cm (8in - 20in)

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The slow worm is a greyish brown lizard, even though they are often mistaken for snakes.

Despite their forked yet flat tongue, their eyelids are a giveaway that these reptiles are lizards. To get away from the predators that come after them, they make their movement smoother by dropping their tails low as they move away.

While female slow worms are brown with dark sides, the males are greyish brown. They are no threat to humans, as they do not bite and only measure about 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!

Here are some of the interesting facts about slow worms:

  • 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, keeping them active predominantly during the day.
  • Slow worms may live longer than any other lizard, reaching a total lifespan of over 30 years outside of captivity.
  • Slow worms can also detach their tails while escaping predators, though they can grow it back.

Slow Worm 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, seems to come from the French word “frele,” which means “weak” or “frail,” perhaps as a reference to their slim body.

Slow Worm 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 body. 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 4 cm long. The bodies of the slow worms are shiny, but the males and females are slightly different. While the male slow worms have greyish-brown in color, the females are brown with have dark sides.

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

Slow worm basks on a green banana leaf

©Frank Neugebauer/

Slow Worm Behavior

While other British reptiles enjoy basking in the sun, the slow worm does not. Instead, they usually prefer to hide under tree 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 they are usually active during the day and rest 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. 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 prefer to thrive within their natural environment, and they are not kept in 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 that want to preserve their plant life.

Slow Worm 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 in 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 compost or dung heaps. Therefore, keeping them as a pet is never a great idea. However, if you still want to keep them, as a pet or otherwise, it would be necessary to create such conditions for them to thrive in. You would have to create conditions much like their natural habitat so that they can naturally thrive in the area. They may be better off in the garden where they can roam and feed freely.

Slow Worm 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.

Slow Worm Predators and Threats

Slow worms are small reptiles, making them a quick meal for many predators. However, one of their biggest threats has previously been humans. Due to their similarity to the snake, many people previously were killing or trading 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 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 they do not eat plants as other worms do.

What Eats Slow Worms?

Due to their small size, these reptiles are prone to be 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, small worms also leave their tails behind while escaping from predators with smoothening the process for them. Not only that, but they are also known to defecate which produces a foul smell and wards off the predators, keeping them safe.

Slow Worm Reproduction, Babies, and Lifespan

Mating is a rather interesting experience for the animal, starting with the male’s biting of 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 ovoviviparous, which means that they lay their eggs internally. The eggs remain in the female’s body until they hatch, allowing the mother to essentially release the live young when they are ready.

After hatching, the young stay in the mother’s womb for a while. While the babies of slow worms are inside the body of the mother, they live off the yolk of the eggs that hatch inside the bodies of the female slow worms.
After a while, however, the female gives birth to the young and the babies finally come to life. Babies of slow worms are usually very thin and are just about 4 cm long. Most births will occur during summer, and approximately 8 young are released at that time.

Slow worms are known to be the longest living out of all the lizards. While their average lifespan is of 15 years, some have also been recorded to have lived for about 54 years.

Slow Worm 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.

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AZ Animals is a growing team of animals experts, researchers, farmers, conservationists, writers, editors, and -- of course -- pet owners who have come together to help you better understand the animal kingdom and how we interact.

Slow Worm FAQs (Frequently Asked Questions) 

Are Slow Worms herbivores, carnivores, or omnivores?

Slow Worms are Carnivores, meaning they eat other animals.

What Kingdom do Slow Worms belong to?

Slow Worms belong to the Kingdom Animalia.

What phylum to Slow Worms belong to?

Slow Worms belong to the phylum Chordata.

What family do Slow Worms belong to?

Slow Worms belong to the family Anguidae.

What order do Slow Worms belong to?

Slow Worms belong to the order Squamata.

What genus do Slow Worms belong to?

Slow Worms belong to the genus Anguis.

What type of covering do Slow Worms have?

Slow Worms are covered in scales.

In what type of habitat do Slow Worms live?

Slow Worms live in grasslands and woodlands.

What is the main prey for Slow Worms?

Slow Worms prey on insects, slugs, and worms.

What are some predators of Slow Worms?

Predators of Slow Worms include cats, dogs, and birds.

What are some distinguishing features of Slow Worms?

Slow Worms have long, snake-like bodies and small eyes.

How many eggs do Slow Worms lay?

Slow Worms typically lay 8 eggs.

What is an interesting fact about Slow Worms?

Slow Worms are found widely throughout British gardens!

What is the scientific name for the Slow Worm?

The scientific name for the Slow Worm is Anguis fragilis.

What is the lifespan of a Slow Worm?

Slow Worms can live for 10 to 30 years.

How fast is a Slow Worm?

A Slow Worm can travel at speeds of up to 0.3 miles per hour.

What is a slow worm?

A slow worm is a type of legless lizard. However, these reptiles are often mistaken for snakes. With close examination, you can see that they have eyelids and ear holes – snakes, on the other hand, do not.

Where do slow worms live?

Slow worms prefer living 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 predominantly found in Britain, but not in the Scottish islands or in Ireland.

What type of animal is a slow worm?

A slow worm is a reptile.

How do you make a slow worm habitat?

Slow worms thrive best in rough grassland like situations. They like to hide under earth or compost heaps. Therefore, it would be necessary to create these common habitual conditions for slow worms to hibernate.

Are slow worms dangerous?

Slow worms are usually not known to be dangerous to humans as they do not bite at all.

Are slow worms carnivores, herbivores, or omnivores?

Slow worms are carnivorous in nature and eat a variety of invertebrates. They usually feed on spiders, snails, slugs, and other small worms.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.


  1. Amphibian and Reptile Conservation, Available here:
  2. Soft Schools, Available here:
  3. Woodland Trust, Available here:
  4. Trees For Life, Available here:
  5. British Trust for Ornithology, Available here:
  6. Wikipedia, Available here:

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