| Grove snail Cepaea nemoralis |
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|---|---|
| Cepaea nemoralis | |
| Conservation status | |
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NE[1]
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| (unranked): | clade Heterobranchia clade Euthyneura |
| Superfamily: | Helicoidea |
| Family: | Helicidae |
| Genus: | Cepaea |
| Species: | C. nemoralis |
| Binomial name | |
| Cepaea nemoralis (Linnaeus, 1758)[2] |
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The grove snail or brown-lipped snail (Cepaea nemoralis) is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc. It is one of the most common species of land snail in Europe and has been introduced to North America.
Cepaea nemoralis is the type species of the genus Cepaea.[3]
It is used as a model organism in citizen science projects.[4]
Contents |
Cepaea nemoralis is among the largest and because of its polymorphism and bright colours one of the most easily identified snails in Western Europe.[4] The color of the shell of Cepaea nemoralis is very variable, reddish, brownish, yellow or whitish, with or without dark brown colour bands.[5] Apertural lip usually dark brown, rarely white.[5] The umbilicus is narrow but open in juveniles, closed in adults.[5] For every colour variant names were established in the 1800s; this was later abandoned.[5] The surface of the shell is semi-glossy, and it has from 4½ to 5½ whorls.
The width of the shell is 18–25 mm.[5] The height of the shell is 12–22 mm.[5]
The animal is moderately slow and not very shy.[5] In Haus der Natur Cismar this species is used to demonstrate snail behaviour to children.[5]
Similar species:
Apart from the band at the lip of the shell, grove snails are highly polymorphic in their shell colour and banding. The background colour of the shell can sometimes be so pale as to be almost white; it can also be yellow, pink, chestnut through to dark brown, and the shells can be with or without dark bandings. The bands vary in intensity of color, in width and in total number, from zero up to a total of six.
The polymorphism has been intensely studied from 1940 onwards for its heredity, evolution and ecology. Researchers have variously asserted that the cause is random genetic drift, different natural selection pressures in different areas (the snail often has darker camouflage in woodland, lighter in rough grassland) with mixing by migration, and balanced polymorphism. Balanced polymorphism could arise when a predator like the Song Thrush has a given 'search image', so it tends to see and kill snails of a particular colour and pattern. Natural selection then favours a diversity of colours and patterns. However it appears that no one explanation is the whole answer: most probably, the polymorphism has several causes, including selection of paler, more reflective colours in hot environments to reduce water loss.[6]
Different coloration and banding of the shells of Cepaea nemoralis:
Its native distribution is from northern and western Europe to central Europe:[7]
Western Europe:
Central Europe:
Southern Europe:
Northern Europe:
Eastern Europe:
No doubt aided by human transport, it is a good colonizer, and is often found in gardens, parks and abandoned land in cities.[4] In eastern Europe it occurs in urban areas. More recently, the grove snail has been introduced to North America,[5] and has established itself in various places. Also in Venezuela.
The white-lipped snail has a similar range, but that species extends further north to border the Arctic.
It is a very common and widespread species in the Western Europe, occupying a very wide range of habitats from dunes along the coast to woodlands with full canopy cover.[4] It lives in shrubs and open woods in plains and highlands, dunes, cultivated habitats, gardens and roadsides.[5] It can be found up to 1200 m in the Alps, 1800 m in the Pyrenees, 900 m in Wales, 600 m in Scotland.[5]
It feeds mainly on dead or senescent plants.[4][5] It is not noxious to crops.[5]
Like most Pulmonate land snails, it is hermaphrodite and must mate to produce fertile eggs.[4] Mating tends to be concentrated in late spring and early summer, though it can continue through the autumn.[4] The snails often store the sperm they receive from their partner for some time, and individual broods can have mixed paternity.[4] In Britain it lays clutches of 30-50 (in France 40-80) oval eggs are laid between June and August (in France May-October, in W France until November).[5] The size of the egg is 3.1 × 2.6 mm[9] or egg diameter can be 2.3-3.0 mm.[5] Juveniles hatch after 15-20 days.[5] Maturity is reached after shell is fully grown, in France after one year.[5] It is comparatively slow-growing, usually taking three years to develop from an egg to a breeding adult.[4] Life-span is up to seven-eight years, annual survival rates at about 50 % (= 3 % in five years, older adults suffer higher mortalities).[5] In winter, the snails may hibernate, but can be active in warm spells.[4]
Parasites:
Predators of Cepaea nemoralis include the Song Thrush Turdus philomelos and others.
This article includes public domain text from the reference[5] and CC-BY-2.5 text from the reference[4]
