Kerry Slug - Behaviour

Behaviour

This species of slug is primarily nocturnal, in other words it is usually only active at night. During the daylight hours, these slugs are usually hidden in crevices of rocks and under loose bark on trees. In Iberia, juvenile slugs of this species become active during twilight, and adults become active at night, especially on rainy or very humid nights. Ireland however is much further north, so the temperatures there are considerably cooler, there is more rain, and the air is often quite damp; in Ireland this slug is sometimes active in the daytime as long as the weather is humid and overcast.

The Kerry slug has a very unusual defensive behaviour. When attacked, most land slugs will simply retract the head and contract the body, but stay firmly attached to the substrate. In contrast, when this slug is threatened, it retracts its head, lets go of the substrate, rolls up completely, and stays contracted in a ball-like shape. This is a unique feature among all the Arionidae, and among all slugs in Ireland.