Invertebrates
Garden Snail
Cornu aspersum · also called common garden snail, brown garden snail, petit-gris
The garden snail is the one everyone knows: a brown coiled shell the size of a hazelnut, a soft grey body, two pairs of tentacles, and a silvery trail across the path in the morning. It is also, on close inspection, a much stranger animal than its familiarity suggests, with a tongue full of teeth, a chalk dart it fires at its mate, and a built-in door it can seal behind itself.
Overview
Cornu aspersum is a land snail with a globular, wrinkled, brown-and-buff banded shell about 3 cm across. It is native to the Mediterranean and western Europe and has been carried around the world with plants and for food. It lives in gardens, hedgerows, parks, and farmland, feeding at night and in wet weather on living and dead plant material, which makes it a familiar garden pest.
A tongue like a rasp
The snail eats with a radula, a ribbon in its mouth bearing thousands of tiny teeth, drawn across a leaf like sandpaper. It also eats soil and old shells for the calcium it needs to grow its own shell.
Mating, and the love dart
Every garden snail is a hermaphrodite, carrying both male and female organs, so any two adults can mate and both then lay eggs. Courtship involves each snail driving a small calcium-carbonate dart into the other; the mucus on the dart improves that snail’s chances of fathering young, and the behaviour is one source of the Cupid’s-arrow image.
Shutting down
In drought or cold the snail withdraws and seals its shell with a dried-mucus lid, the epiphragm, then rests with its metabolism slowed for weeks or months until rain returns. It navigates back to the same resting spot each day by following slime trails.
Status
The garden snail is Least Concern and enormously abundant, with no conservation concern — in many regions it is treated as a pest instead.
Garden Snail: common questions
Are garden snails male or female?
Both, at the same time. A garden snail is a simultaneous hermaphrodite, meaning every adult has a functioning set of male and female reproductive organs. When two snails mate, each one can transfer and receive sperm, and afterward both partners can go on to lay a batch of eggs in a hole in moist soil. This doubles the reproductive output of an encounter and means any two mature snails are potential mates, which is useful for a slow-moving animal that may not meet many others. Self-fertilisation is possible but uncommon, and snails generally seek a partner.
What is a snail's love dart?
It is a small, hard, arrow-shaped structure made of calcium carbonate, a few millimetres long, that garden snails and many of their relatives use during courtship. Before mating, one snail stabs the dart into the body wall of the other. The dart itself carries a mucus that, once inside the recipient, changes the shape of part of its reproductive tract so that more of the dart-firer's sperm survives to fertilise eggs. It is essentially a device for winning at sperm competition. The behaviour, in which snails appear to shoot each other with tiny darts during a slow embrace, is one origin of the image of Cupid and his arrows.
How do garden snails survive dry weather and winter?
They shut down and wait. When the air becomes too dry, or too cold, the snail pulls fully into its shell and secretes a layer of mucus across the opening that dries into a thin lid called an epiphragm, sometimes reinforced with chalk. Behind this seal the snail's metabolism drops steeply, water loss almost stops, and it can remain dormant for weeks or, in a severe drought, months, a state called aestivation in summer and hibernation in winter. Snails often cluster together in sheltered spots, glued to walls or under pots, to ride out the bad conditions, then become active again after rain.
How do you keep garden snails off plants without poison?
Several non-chemical methods help, usually in combination. Physical barriers work because snails dislike crossing certain surfaces such as copper tape around pots and beds, sharp grit, crushed eggshell, or wool pellets. Removing daytime hiding places such as loose boards, dense ground cover, and pot rims near vulnerable plants reduces numbers. Watering in the morning rather than the evening leaves the soil surface drier at night when snails are active. Encouraging predators, including song thrushes, hedgehogs, frogs, ground beetles, and slow worms, keeps populations down. Hand-collecting after dark or after rain, especially in spring, removes breeding adults before they lay.