Swedes Confused About Slugs


All multicellular land species of life in Scandinavia are invasive: the area was covered by kilometres of ice until yesterday, geologically speaking. But some species are more recent invaders than others. Where I live, we currently have three species of large-bodied snail or slug: the Black slug (Arion ater, Sw. svart skogssnigel), the Burgundy snail (Helix pomatia, Sw. vinbergssnäcka) and the Spanish slug, (Arion vulgaris, Sw. spansk skogssnigel). That's the order in which they arrived: the Blacks during prehistory, the Burgundians most likely during the Middle Ages, and the Spaniards from 1975 onward.

Now, both of our two species of slug vary a lot in their looks, and their ranges of variation coincide to such an extent that the public can't tell them apart. The only rule seems to be that unlike the Spaniards, some Blacks are really coal black. Out of 1200 specimens of suspected Spaniards submitted to the Gothenburg Museum of Natural History in the 1980s, 60% were actually endemic Blacks. But they behave differently: the Spaniards are serious garden pests and not very cold-tolerant, while the Blacks are less problematic to gardeners but more hardy. Also, the Spaniards are notable for cannibalism, giving them the ominous vernacular name "Killer slug", Sw. mördarsnigel.

To my annoyance, many people born after the Spaniards came to Sweden now don't know that the Black slug exists and is no great problem for gardeners. Yesterday I saw a little girl kill a slug she found on a bike path. When I asked her why, she explained that it was a killer slug and must be killed, or it would ruin somebody's garden. "Killer slugs are brown, have no shell and look like turds." She'd never heard of the Black slug. When I explained that most slugs that look like turds are not killer slugs, she asked, "So how do I tell them apart?". "You can't", I replied.


More like this

I have heard that slugs are good for dating archeological findings sometimes. In the Landscape Mysteries BBC series, that is one method for dating the supposed prehistory chalk figures in Britain. Since slugs these that you mentionen have no harder parts I was stunned by how this was done. An explanation was acids from these slugs?

By Thomas Ivarsson (not verified) on 12 Aug 2011 #permalink

That slug looks like it should taste of liquorice ...

By nick williams (not verified) on 12 Aug 2011 #permalink

Ahh ... the mythic tales of noble heroes fighting the vicious, ravening monster. Kind of loses something in translation if one was to learn that Grendel was a slug scarcely longer than a finger. Pretty big as slugs go and, one would hope, of the "Killer slug" variety; although your timeline clearly says it was more likely a black.

There is some amount of lively debate as to how Grendel the slug "defeated" the warriors of the mead hall of Hroðgar. On one hand you have the story that through an unfortunate mistake in selection of mushrooms the warriors were tripping balls and laying down when a large slug forced a retreat. Grendel the slug, which certainly would seem more formidable viewed while prone and hallucinating, caused them to crawl off in a panic. The accident ingestion of hallucinogenic mushrooms would certainly goes a long way toward explaining Norse mythology.

On the other hand there is the version in which Grendel sneaks in, cunningly falls into a cask of mead, and is victorious after the clogged causes an assumed lack of social lubricant. This causes vicious infighting, hurt feelings, and a general loss of interest that cause the warriors of Hroðgar to disband.

Either way it is Grendel the slug 1 - warriors of Hroðgar 0. Another strange but true story of human slug interaction. In future editions I will show how slugs inspired Newton, that apple didn't just fall on its own volition, how slugs made the industrial revolution possible, think black grease, and how all secret societies can be tracked back to the communal slug over-mind.

Yes, it must be snails in that BBC series. Tracing slugs was a suggestion that I read on a Swedish Archeologica Forum.

By Thomas Ivarsson (not verified) on 12 Aug 2011 #permalink

My conventional wisdom (in Sweden) is that killer snails are brown, and forest snails are black. So that isn't true? Bohoo.

Swedes confused about fauna. The indiscriminate killing of harmless snakes seems to be a national pastime as well. "Nasty piece of work. Might've bitten the kids".

Hmm, the sequel to the science/fantasy novel "Hiero's Journey" from the 1970s has a benign telephatic presence guding the hero past the numerous dangers of a post-apocalyptic society. This presence is later revealed to be a huge telephatic slug.

If the killer snails are potential cannibals, can we make some rabies-like virus able to turn their small brains into "zombie mode"? Then the snails will become self-exterminationg.

Snakes of either kind (adders and the "snok") are harmless to humans -even children-, but the adder venom can kill cats and dogs from liver failure. I wish the DNA boffins can cook up a vaccine blocking the venal molecules soon.

If you meet the Black Adder I strongly recommend a shotgun, as he is the most untrustworthy Englishman ever to emerge from TV.

By Birger Johansson (not verified) on 14 Aug 2011 #permalink

"Swedes confused about slugs" strikes me as an excellent name for a band...

@ Birger Johansson - you're the first person I've known to have also read Hiero's Journey and its sequel. I enjoyed those books. Efforts have been made at various times in various places, including New Brunswick, Canada (I've seen old photos) to make moose into riding beasts, but it seems to be consistently successful you'd need telepathy at least. Moose can be a bit - er - headstrong.

And the slugs here are terrible garden eaters which also cannibalise at least their dead relatives - I've seen it often.

By b.ternarius (not verified) on 19 Aug 2011 #permalink

My dear Martin,
you are a good illustration to the confusion.
There is also a brown Scandinavian slug "Brun skogssnigel, (Arion fuscus (synonym Arion subfuscus))" which - unlike the black is easily confused with young specimen of the Iberian Arion vulgaris.

By Göte Svanholm (not verified) on 13 Nov 2012 #permalink

Wikipedia states that the normally black A. ater occurs in brown varieties that are easily confused with A. vulgaris.