On the Origin of a Species – The Slow Worm, Anguis fragilis

The slow worm, this was a large male – you can tell from the uniform browny-grey colouration. He was probably 30-40cm in length, it’s hard to tell as he was coiled a little, but what a beautiful little creature. He was chilling on a footpath up to the hills and cliffs near me. (Credit: Me)

Its name is ‘slow worm’ when it is neither slow, nor a worm. Other names for it are the ‘deaf adder’ when it neither deaf, nor an adder. Perhaps ‘blind worm’ is the appropriate name, then? Well it can see, and, as mentioned, is not a worm. An archaic term for it is the long-cripple – well it can be quite long but I assure any ableists out there it is far from ‘crippled’.

Even if its Latin binomial, Anguis fragilis, effectively means ‘fragile eel’ when it is not fragile and it’s not a fucking eel!

So what’s the deal with these guys, why have we given them a bunch of names all of which are plain wrong?

Well perhaps the fragilis comes from their ability, as we saw with the common lizard, to autotomise. That is they can shed parts of their body, usually their rear parts, the tail, to escape predation. The tail even keeps writhing for a few minutes to distract the predator. Far from making this little beastie fragile it makes it quite tough! Imagine if you got in a fight and could just pop your arm off without worry knowing you could grow back a new one. That’s not fragility it’s a fucking superpower! Sadly it’s a one-time only deal and the tail that grows back is usually shorter than the one lost.

He was a thiccboi though! Some solid girth to him. I’m no expert so I couldn’t predict an age. Given how stumpy his tail was I suspect he has already shed it once at some point. (Credit: Me)

As for the rest of it, well it’s because it’s a long, wormy sort of thing. It’s not a snake, a remarkably common misconception from people who I think need a ‘We Lack Discipline’ article on taxonomy! They are in the same order as snakes, the Squamata, this order includes a lot of obviously unsnakelike things. Geckos and iguanas are Squamata and nobody says “Ooh look, it’s a snake with legs!”

Again, like with the common lizard, I can remember being fascinated by slow worms from an early age. It was an event to see one, like some small piece of exotica had come to us from a far-off land.

The slow worm has to be one of the most fascinating reptiles in the world. That might seem a stretch but that’s because they are very much taken for granted. It’s too small to be taken seriously as a snake like beast, too snake-like to be taken seriously as a reptile and when they are seen they are usually doing very little hanging around under rocks or in the undergrowth or just basking in the sun.

This girl was quite shy, deciding to coyly hide her face behind a leaf. (Credit: Me)

However their family, the Anguidae, have a fossil record dating back around 75 million years, to the late Cretaceous period, where they would have shared the earth with dinosaurs. Their genus, Anguis, likely evolved around 50 million years ago during the early Eocene. The lineage of these little reptiles saw off the strife that led to the extinction of so many species, included the dinosaurs, to chill out in our gardens in the UK today.

For as much as they may seem chill we mostly see them when they’re basically charging their batteries. They are voracious predators and you want them if you’re a gardener! They are a carnivorous species that feed mainly on invertebrates. After basking for the day, raising their body temperature, they go off on their dusk raids where they usually go after slugs, small snails, worms and the occasional insect (just a little insect, as a treat!). One of the reasons I often extend my walks into the evenings now is in the hope of seeing lizards and slow worms actually hunting!

These guys will eat the things you curse for munching at your flowerbeds or your cabbages – with no need for cruel and soil-harming salts, pesticides, insecticides or repellents. They are a charming natural slug remover!

This one looks like quite a large boy, snapped in Swansea. (Credit: © Copyright Dave Croker CC-BY-SA 2.0)

They are what we would call ‘semifossorial’. They’re burrowers, and if not basking in the sun they can often be found under large bits of wood, dense leaf litter, stones, rubble etc. Anywhere they can find a nice, warm hidey hole. In fact they are more likely to be warming underneath something than out in the open.

I believe I have mentioned my brother has a breeding mother regularly in his garden and cultivates families of slow worms. I’ve seen the whole group of them, mum and babies, chilling out under a stone. It’s beautiful.

They tend to hibernate (usually underground) between October and March so April-September is the best time to see them. Whilst they do have their own individual characters, some being happier to be prodded and bothered than others, I do advise being careful, do not handle it if not necessary (i.e. to protect it for some reason) and just leave it in peace. Even the one I saw was uncomfortable getting a camera shoved in its face and quickly spun around and disappeared into the long grass where I, clumsy, overgrown human twat that I am, am ill-equipped to follow.

You can usually tell sexes apart by appearance. The males are an almost uniform grey-brown, whilst the females are a beautiful gilded brown with darker flanks and sometimes a distinctive faint stripe on the head or down the back. I have personal photos from a female seen in my brother’s garden (the mother who is always having babies there) and the male I saw whilst on a walk so you can look to compare them.

The female in my brother’s garden. More golden in colour with distinct dark stripes down the sides (young of this species have the same colour pattern, regardless of sex) the stripe that usually runs down the back is faded in this girl. (Credit: Me)

Like the common lizard, and unsurprising given the common habitat they share for a lot of their range, they give birth to live young. These tiny little wigglers are absolutely adorable.

I wish I had some danger with which to discourage you from bothering slow worms but, as far as we know they don’t bite humans so they are of no danger to us.

In fact, we are the danger. Habitat loss has caused a decline in their numbers in the wild, whilst urban and suburban populations are prone to predation by cats and can often be found dead, with their extremities missing. My old cat, the late, great Smooze used to have a distinctive howl when she would find a reptile and I’d immediately dart down, chase her off it and ensure it got to a safe place!

They can grow up to 50cm in length but size is not their specialty. That would be longevity. How do we know my brother has the same mother slow worm breeding in his garden? We don’t! It’s hard to tell them apart. But there is one in the same place almost every year and in the wild we know they tend to live to be about 30 years old. The record is a specimen from Copenhagen Zoo captured in 1892 that died in 1946, at least 54 years old.


Look at this gorgeous girl from Hertfordshire. Not sure what settings have been used but it really sets off the golden-brown hue of their skin. Their scales do not overlap, like those of snakes. This makes them very smooth to the touch. (Credit: Peter O’Connor aka anemoneprojectors, CC-BY-SA 2.0)

In the UK they are a protected species. It is illegal to intentionally kill, harm, sell them or advertise to sell them under the Countryside Act 1981. So, please, I know they may seem tame and harmless – it’s because they are! But if you bother them you can end up with the police knocking on your door.

If you want to see them, to have some as garden buddies, well then I have some suggestions. Putting down a heavy slab or stone or two somewhere in your garden may help. If you can’t afford to make yourself a small rockery then a sturdy piece of dark plastic or a sheet of tin or corrugated iron will also do the job. Be careful not to disturb them too much (or they may piss off) and be careful when replacing their shelter as they are easily crushed or harmed. They love to hang out under things, especially warm things – but be careful where you live and when you lift to check, because so do adders and unlike slow worms, whilst they are mostly harmless too, adders can bite!

A juvenile slow worm – the species is ovoviviparous – this means the mother effectively incubates her eggs inside herself and only ‘gives birth’ after they have hatched. All slow worm young, regardless of sex, have a similar black-and-gold colouration, with dark flanks and bellies and a shiny golden top, similar in colour to a female. (Credit: Stijn99 CC-BY-SA 4.0)

So I have been very lucky, over the last few weeks I have seen two of Britain’s incredible, native reptiles. Chances are I’ve been close to adders, too, but they are notoriously shy! It is still my mission to see them all and after having seen them, to tell you about them.

But slow worms really are precious little things so do your best to help them out, don’t bother them and try to keep your cats away from them!

Want to read about more animals? Read more from our ‘On the Origin…’ Series!
Saltwater Crocodiles – Beautiful, potentially human-hunting, predators.
The Tapiridae – The tapirs, amazing, prehistoric looking animals.
The Common Lizard – Maybe common, but a rare sight as they are shy!
The Red Panda – What is it? Some of kind of raccoon-bear-cat!? Nope, it’s a cute panda.

Or check out our Top Ten Animals Series
The Top Ten Sharks – Including the White Shark, Greenland Shark and Whale Shark.
The Top Ten Cats – From the Lion to the domestic Moggy we rank cat species!
The Top Ten Most Hated but Misunderstood Animals – Because they all need love!

We also have a LOT of cats in our Caturday Specials!

Published by Karl Anthony Mercer

Like a dark-chocolate fountain at a weight loss party, Karl Anthony Mercer is an under-utilised river of bittersweetness. When not busy researching or writing about any and all non-fiction topics for 'We Lack Discipline' Karl can often be found walking, staring at wildlife or writing poetry.

One thought on “On the Origin of a Species – The Slow Worm, Anguis fragilis

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: