page_title: Kerry slug
section_title: Behaviour
hierarchical_section_title: Kerry slug / Behaviour
caption_attribution_description: English: Drawing of Geomalacus maculosus as coiled in alarm.
context_page_description: The Kerry slug or Kerry spotted slug is a species of terrestrial, pulmonate, gastropod mollusc. It is a medium-to-large sized, air-breathing land slug in the family of roundback slugs, Arionidae.
  Adult Kerry slugs generally measure 7–8 cm in length; they are dark-grey or brown with yellowish spots. The internal anatomy of the slug has some unusual features and some characteristic differences from the genus Arion, also part of Arionidae. The Kerry slug was described in 1843—later than many other relatively large land gastropods present in Ireland and Great Britain—an indication of its restricted distribution and secretive habits.
  Although the distribution of this slug species includes south-western Ireland—including County Kerry—the species is more widespread in north-western Spain and central-to-northern Portugal. It is not found in locations between Ireland and Spain. The species appears to require environments that have high humidity, warm summer temperatures and acidic soils with no calcium carbonate. The slug is mostly nocturnal or crepuscular but in Ireland it is active on overcast days.
context_section_description: The Kerry slug is primarily nocturnal. During daylight hours, the slug usually hides in crevices of rocks and under loose bark on trees. In Iberia, juvenile Kerry slugs become active during twilight and adults become active at night, especially on rainy or very humid nights. Because Ireland is much further north and has a considerably cooler, wetter and more humid climate, the Kerry slug is sometimes active there in the daytime if the weather is humid and overcast.
  The species has in unusual defensive behaviour; whereas most land slugs retract the head and contract the body but stay firmly attached to the substrate when they are attacked or threatened, the Kerry slug retracts its head, lets go of the substrate and rolls itself into a ball-like shape. This is behaviour is unique among species in Arionidae and among slugs in Ireland.
caption: The alarm response posture, which is found only in this species
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