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Invertebrate of the Month
Geomalacus maculosus, Allman, 1843 »

Slugs are not considered the most appealing of animals especially the pest species in gardens. This species is however an attractive exception and it is also one of the most interesting invertebrate species found in Ireland. The Kerry Slug has a very restricted global range, existing only in Ireland, Spain and Portugal (where it is possibly extinct) and is often cited as a zoological example of a Lusitanian species. It was described in 1843 from specimens found at Lough Caragh in Kerry.

The slug is attractively marked with white or yellow spots. Two colour forms exist, a blue/grey one with white spots and a ginger or brown form with yellow spots. Both varieties coexist in Ireland at least.

The habitat of the Kerry Slug in Ireland is woodland and bogs within the sandstone areas of Kerry and west Cork. It is absent from limestone areas. Within woodland the adults can be found on tree trucks and boulders always close to water.

Kerry Slugs are active most of the year at night, but also commonly during daylight, especially during and just after rain. At other times they hide in crevices, under dead bark and stones. The animals are very elastic and can squeeze into very small gaps. They also have the habit of curling into a ball like a woodlouse. Adults have lived for over 6 years in captivity. The diet is principally algae, lichens, mosses and liverworts which they graze off rocks and trees.

Geomalacus maculosus (Kerry slug)

Geomalacus maculosus

© Roy Anderson

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