page_title: Kerry slug
section_title: Description
hierarchical_section_title: Kerry slug / Description
caption_attribution_description: English: Drawing of right view of the posterior part (tail end) of Geomalacus maculosus. Ethanol preserved specimen.
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 body length of adult Kerry slugs is 7–8 cm (2.8–3.2 in). These slugs are difficult to measure accurately because of their unusual startle response. Kerry slugs can also elongate themselves within crevices up to 12 cm (4.8 in). Official measurements of this species vary; Kerney et al. (1983) give a range of measurements of 6–9 cm (2.4–3.6 in). The body of a fixed (preserved) adult specimen was 7 cm (2.8 in) long with a mantle length of 3 cm (1.2 in).
  The body of the Kerry slug  is glossy and is covered on both sides with about 25 longitudinal rows of polygonal granulations. The slugs have two colour morphs, brown and black. In Ireland the black morph occurs in open habitats and the brown morph occurs in woodland; this correlates with the colours of the surroundings, suggesting camouflage. Experiments indicate the dark colouration is induced by exposure to light as the slug develops. There is also variation in banding; on each side of the body there can be two bands: one band just below the summit of the back and the other band further down the side of the body. When these bands are present they usually extend the whole length of the body and are overspread by numerous, ovoid yellow spots that are distributed approximately in five longitudinal zones.
  Behind the animal's head is the shield-shaped outer surface of the mantle, which is about a third of the length of the body when the slug is actively crawling and thus extended; when the slug is stationary and contracted, the shield is about half the length of the body.  The front of the shield is rounded and its rear is bluntly pointed. The surface texture of this area resembles the underside of undyed leather; it is spotted with pale, buff or light-coloured spots that are similar to those on the body but are more uniformly distributed.
  The foot fringe, a band of tissue around the edge of the foot, is not distinctly separated; it is very pale and somewhat expanded and has indistinct lines on it. The sole of the foot is pale grey-yellow and is divided into three indistinct bands; the mid-area is somewhat darker and more transparent than the side bands. There is a caudal mucous pit situated between the foot and the body on the upper surface of the tip of the tail. The pit, which collects extra mucus, is not conspicuous, triangular and opens transversely. The mucous pit often carries a transparent, yellowish ball of mucus.
  The Kerry slug's upper tentacles are smoky-black or grey, short and thick with oval ends, and have eye spots at their tips. The genital pore or opening lies behind and below the right eye tentacle. The lower tentacles are pale-grey and translucent. The skin mucus is usually pale yellow and varies in viscosity. The locomotory mucus is tenacious and usually colourless but is sometimes yellow because of mixing with body slime.
caption: Right view of the tail end of the body.
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