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Species native to the United Kingdom
Introduced or alien species
Alien species that present a threat to wildlife

Slow-worm - Anguis fragilis - Native



Legless Lizard

Males and Females show a marked difference in colour when fully grown.

Females very often have a dark vertebral (back) stripe, the flanks are flecked or striped with dark brown or black, the ventral surface is nearly always uniform black.

Slow-worm - female
Original Image © Fred Holmes

Adult males are more uniform in colour dorsally and on the flanks, the belly is usually mottled black or dark grey, they also have proportionally larger heads. Occasionally males have very distinct blue spots.

The upper parts of the body vary from light or dark brown, grey, bronze or brick red.

Length: 40 - 45cm

Male Slow-worm showing blue spotting
Slow-worm - blue spotted male
© Tony Phelps Reptile Research & Imagery

Breeding and young

Emerging from hibernation in March, the slow-worm may be seen to bask in the early morning and evening sun, as the animals come into condition for breeding, which occurs in May. The young take 4 - 5 months to develop, being produced in late August to early September. The Slow-worm is ovi-viviparous, meaning that the young are born in an egg membrane that breaks soon after birth.

The young of both sexes are a pale golden-brown or greyish silver above, the sides and belly are pitch black. A small spot or blotch on the head leads to a continuous black stripe down the entire length of the back. It is usually only the males that loose this stripe marking as they reach sexual maturity at around 3 years.

Between 3 and 26 young are produced, the average is 8. New born slow-worms appear remarkably small, being between 70 and 100 mm in length at birth.

Sub-adult Male slow-worm showing loss of vertebral stripe.

New born slow worm showing golden colouration and dark blotch on head, leading to a dark vertebral stripe.

New born slow worm showing grey-silver colouration, note the pitch black flanks.
Slow-worm - sub-adult male
© 2003 Gemma Jane Fairchild RAUK

Slow-worm - new born - golden
© 2003 Gemma Jane Fairchild RAUK

Slow-worm - new born - silver
© 2003 Randall Hardy - Creation Research

What else could it be?

The Slow-worm is often mistakenly thought to be one of our native snakes. Slow-worms have very few markings other than the vertebral stripe of the female. This is thin and straight and not similar to the indented zigzag stripe of the Adder (Vipera berus).

The Slow-worm has a noticeably blunter tail than any of the native snakes and the head is quite indistinct from the body. They have very small, highly polished scales, giving a glassy appearance.

On very close examination, it might be seen that the Slow-worm has eyelids, a typical feature of lizards. Another typical feature of lizards displayed by them, is the shedding of the tail when captured. The shed tail falling to the ground and thrashing makes a very effective decoy to predators, whilst the Slow-worm makes for cover.

The Slow-worm is a harmless creature, please remember, whether it is a Snake or Legless Lizard, it is a criminal offence to kill or injure any of the UK's native reptiles.

Male Slow-worm showing the more uniform colour and less defined markings as compared to our native snakes, indistinct neck, small scales and glassy appearance.

Slow-worm - adult male
© 2003 Gemma Jane Fairchild RAUK

Where will I see a Slow-worm?

Very widely distributed in Britain, adults spend much of their time under ground in burrows they make for themselves, they are highly elusive yet not uncommon. They may be seen along railway embankments, in wooded areas, church yards, waste ground and allotments.

They very often live in gardens unnoticed, making use of compost heaps for their burrows and feeding on slugs and snails.

Slow-worm showing eyelids.
Slow-worm - head
© Tony Phelps Reptile Research & Imagery

Slow-worms are protected under the Wildlife and Countryside Act 1981.

It is an offence to kill, harm or injure them

sell or trade them in any way

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