The Ghosts of Ysgol Pencae

By OPAL Community Scientist, Barbara Brown

“There’s a slug! And a worm!" shout a group of Year 3 pupils in the middle of their OPAL bug hunt in Ysgol Pencae’s vegetable garden.

I lean over their shoulders and help the clipboard holder to record it. Then I look for the slug. “There it is – its white!” says the group’s recorder. 

It is very white, perhaps the purest white slug I have ever seen. Which makes me wonder, so I pick it up.

“Urgh – she’s picked it up!” chorus the group. I laugh and say: “It’s not very slimy, it's ticklish”.

It does tickle actually. It seems to be trying to squeeze through the gap in between my fingers. Something around the tip of the head feels rough on my fingers.

Quickly I snap a photo with the help of the group and go on and help the other bug hunters with their recording sheets.

Ghost slug held in hand

Ghoulish creature

Back at the office on Monday morning I send the photo to Ben Rowson, Museum of Wales’ slug expert. He emails me back straight away to say I have found another record of Selenochlamys ysbryda... the Ghost Slug.

The Ghost Slug was first described by Ben in 2008, from a handful of records in Cardiff and Caerphilly. It is a carnivorous slug which eats earthworms and it was perhaps its rasping teeth that I felt on my fingers. It hunts worms underground, by squeezing through cracks and tunnels up to 1 metre underground, where it spends most of its life. This makes it very difficult to find, especially as its occasional surface apparitions are nearly always at night.

It has no eyes and this is the most characteristic feature for identification. Most slugs have eye-spots on their antennae, but the Ghost Slug is a blind assassin. This strange creature can also suck its own head inside out and breathes through a hole in its tail.

Ghost Slugs have no eyes on their antennae

A long way from home

However the biggest mystery about the Ghost Slug is how it got to South Wales, as its only other home is the mountain forests of Crimea!

DNA analysis of 6 UK specimens has revealed that they have almost identical DNA sequences, which suggests they are all descendants from a small colonising population. They may have all travelled on a few imported plants. Exactly how and when they arrived will probably never be known – and it is probably fanciful to invoke a connection with the Cwmbran suburb of Sebastopol.

It does seem to be spreading in the UK, as an appeal for sightings led by National Museum of Wales yielded a record in Wallingford, Oxfordshire, but nearly all the other records were based in South Wales, and due to its nocturnal surfacing, the exact extent of its reach it likely to remain unknown.

Image credits: Barbara Brown/OPAL and Amgueddfa Cymru - National Museum Wales.

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