This burrowing slug, which grows up to 4 inches in length (6-12 cm) was discovered in the National Botanic Gardens Car Park in Septmeber 2008 by Slug expert Gery Holyoak. It was last seen in Ireland in 1931, and before that in 1892. They are rarely seen because they spend much of their lives burrowing in the soil, and only emerge at night to prey upon slugs, snails, centipedes and worms.
Although we tend to think of slugs and snails as very disitnct creatures in Ireland, there are in fact numerous different grades of shell reduction, one of which are the so-called shell slugs or half-slugs – slugs with a tiny little rudimentary shell at the end of their tails, into which they cannot withdraw.
The shelled slugs find their favourite prey, other slugs and earthworms, by smell. Once they catch up with a worm, their backward pointing, dagger-like radula teeth never allow it to escape, and the slug gradually swallows the entire worm whole and digests it alive.