What is it about slugs that so repels us? After all, they are closely related to snails, with their pretty shells and (to some) their associations with gastronomy.
Their other relatives, shell-forming marine invertebrates from around the world, are highly desirable to collectors who want to own their exquisitely beautiful protective armour. But a slug?
Even the word ‘slug’, which is spat rather than spoken, describes something base or corrupt: a slow and lazy person; a gulp of rough liquor; a bullet; a counterfeit coin; a punch.
Despite all of the adjectives at our disposal to describe these soft, glistening, moist, succulent, flexible, sleek and tender creatures, the only one that most people can come up with is ‘slimy’.
The reason why slugs suffer from such a poor image is, unfortunately, abundantly clear: they have the temerity to wear their slime on the outside, rather than on the inside like the rest of us.
So, it’s time to give these much-abused animals a PR makeover.
Here are six things you didn’t know about these amazing molluscs:
- If you’re a keen gardener, it’s no good just hunting the big ones. Pheromones in their slime trails tell junior slugs that large slugs are around; killing them simply frees up space for small individuals to move in.
- Slime trails are a tactical compromise. The slug loses water in its mucus, which restricts its activity to the cool damp of night or to rainy days, but the lubrication that slime offers saves energy that would otherwise be needed to overcome friction.
- Unlike snails, no slugs live in fresh water (sea slugs evolved separately, also losing their ancestral shells).
- Though soft-bodied, slugs are hard-toothed. Each has an oral cavity that contains as many as 100,000 tiny teeth on the ribbon-like radula, or tongue.
- Slugs may look smooth, but sometimes that’s an illusion – a few are covered in soft prickles. One such species is the hedgehog slug, Arion intermedius.
- Britain is home to the world’s largest slug: Limax cinereoniger. Found in southern and western woods, it reaches up to 30cm when fully extended.
The UK’s 30 or so slug species come in all sizes, shapes and colours. Here are seven to look out for:
Great grey or leopard slug Limax maximus
Very large, up to 20cm. Various shades of grey, with pale tentacles. Mantle is raised at the head end. Woods, hedges and gardens.
Large black slug Arion ater
Very large, up to 15cm. Colour varies through brown to bright orange. Fields and gardens.
Budapest slug Tandonia budapestensis
Small, up to 6cm. Brown to grey overall; long ‘keel’ along back is usually lighter than rest of body. Common in gardens.
Yellow slug Limax flavus
Medium-sized, up to 9cm. Yellow or greenish overall, with bold, steel-blue tentacles. Common in gardens.
Garden slug Arion hortenis
Small, up to 4cm. Blue-black overall; the sole of the foot and mucus are yellowish-orange. Common in gardens.
Common grey field slug Deroceras reticulatum
Small, up to 5cm. Pale cream to dirty grey; the breathing pore has a pale rim. Fields.
Shelled slug Testacella haliotidea
Medium, up to 8cm. Pale whitish-yellow. Narrower at head than tail end, with a small shell. Often in old compost heaps; secretive.
You can discover more about slugs by visiting the Conchological Society of Great Britain and Ireland.