Garden snail  (Helix aspersa)

Common and widespread (2).

This snail is very common and widespread, and is the typical garden snail (1). The shell is generally spherical in shape with a short spire and a 'wrinkled' surface (3). It is pale brown, or yellow in colour (3), and is marked with a number of broken dark bands that give the shell a blotched appearance (2). The thickened lip around the large opening, or 'aperture' of the shell is white in colour (2).

The garden snail is found throughout most of lowland Britain (1). Elsewhere, it has a wide distribution, and is found across the Mediterranean area, in parts of western Europe, North Africa, and Asia Minor (2). It has also been widely introduced, and has become established in some areas of the USA (4).

Very often associated with humans, and can be found in parks and gardens. It also inhabits woods, hedgerows and dunes (3).

This snail is mainly nocturnal but will emerge after rain during the day. It moves by means of a muscular foot; the mucus secreted by the foot aids with movement and leaves a tell-tale track behind. They feed on a range of plant matter, and can be serious pests of gardens (4). This snail has a strong homing instinct, and spends the day, often in large groups, beneath stones and other structures. They hibernate through the winter in similar locations (5).

Garden snails are hermaphrodites, meaning that one individual possesses both male and female reproductive organs; although they are able to self-fertilise, most snails mate with another snail (4). Reproduction takes place in early summer, and begins with pairing and courtship. After a period in which the members of the pair caress each other with their tentacles, each snail pierces the skin of its partner with a calcareous 'love dart', a spiny projection which is covered in mucus. The function of this love dart is unclear, but it is thought that the mucus may act to improve the survival of sperm. Mating then takes place; each snail inserts its penis into its partner at the same time (6). The snails separate, and the sperm is stored internally until the eggs are ripe. After the eggs have been fertilised, the snails dig pits in the soil in which to lay the eggs (5). Hatchlings have translucent, delicate shells (4).

The garden snail is edible, and snail farming is currently a booming cottage industry in Britain. This species has also been used for centuries in traditional medicine, for example, broth made from the mucus was used to treat sore throats (7).

Not currently threatened.

Conservation action has not been targeted at this species.

For more on invertebrates and their conservation see Buglife, the Invertebrate Conservation Trust at:
http://www.buglife.org.uk/

• Calcareous: containing free calcium carbonate, chalky.
• Hermaphrodites: possessing both male and female sex organs.
• Hibernate: a winter survival strategy characteristic of some mammals in which an animal's metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is 'diapause', a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pupae or adults) may enter diapause, which is typically associated with winter.
• Nocturnal: active at night.
• Self-fertilise: fusion of male and female sex cells (gametes) from one individual. In contrast, in cross-fertilisation, two different individuals are involved.

1. National Biodiversity Network Species Dictionary (March 2003): http://www.nhm.ac.uk/nbn/
2. Pfleger, V. & Chatfield, J. (1983) A guide to snails of Britain and Europe. The Hamlyn Publishing Group Ltd., London.
3. Kerney, M.P. & Cameron, R.A.D. (1979) A field guide to the land snails of Britain and north west Europe. William Collins Sons and Co. Ltd., London.
4. Brown garden snail: University of Florida Department of Entomology and Nematology. (March 2003): http://creatures.ifas.ufl.edu/misc/gastro/brown_garden_snail.htm
5. Janus, H. (1982) The illustrated guide to molluscs. Harold Starke Ltd., London.
6. Koene, J. M. & Chase, R. (1998) Changes in the reproductive system of the snail Helix aspersa caused by mucus from the love dart. The Journal of Experimental Biology, 201: 2313-2319.
7. Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.