Garden snails travel at about 50 yards in an hour, but, as David Profumo reports, they are notoriously promiscuous hermaphrodites that enjoy a protracted mating ritual.

Aterrestrial mollusc trailing loathly slime, yet crowned with a shell of logarithmic perfection, the common or garden snail is detested by gardeners, but has inspired centuries of human fascination. All snails evolved from the sea and Helix aspersa is one of 80,000 species that have established themselves everywhere from the Atlantic trenches to the Himalayan peaks. It belongs to the class Gastropoda, signifying ‘belly foot’: the body is soft, unsegmented and greyish, its pimply shagreened skin coated in mucus.

The head sports two pairs of retractable horns its vision via one set of conning towers is dim, but the powers of touch and smell are acute. A dark mantle shields the cavity containing its lungs and heart (the blood is faintly blue) and malacologists reckon that, although it possesses no definable brain, the linked ganglia of a snail allow it to make simple decisions.

Globular, horny and pale brown with gingerbread tints, the garden snail’s shell is a conical tube coiled into a protective spiral, usually comprising five dextral (clockwise) whorls. This spectacular secretion an integral part of the animal enjoys continuous growth from the egg stage onward, offering a waterproof refuge into which the creature can withdraw entirely re-emerging by forcing blood into its powerful foot.

Locomotion is achieved by a rhythmic series of muscular contractions, at a proverbially slow rate: snails can ‘gallop’ 50 yards an hour and the adhesive slime allows its ventral foot to proceed upside down or across razor-sharp surfaces. There is a pronounced homing instinct and Aspersa is largely nocturnal, thus minimising desiccation and predatory perils such as hedgehogs, ants and the thrush’s anvil.

They require humidity and, when the ground-level climate becomes unfavourable, snails enter dormant phases (both overwintering and aestivation), their shell’s aperture sealed with a plug of hardened mucus. Enthusiastic herbivores, they inhabit woodlands, parks and gardens and have a fondness for limestone (which promotes shell building). Devastating pests in citrus groves, they also browse on cereal crops, vegetables, precious dahlias and hostas. Some gardeners recommend coffee grounds and copper tree bands as deterrents.

The snail’s long, necessarily loopy digestive tract is fed from a mouth equipped with a chain-like rasping tongue (the ‘radula’) that has 15,000 recurved teeth a lot of dentition for one kitchen garden. When it comes to sex, we’re looking at Fifty Shades of Snail. A notably promiscuous hermaphrodite with extraordinarily complex genitalia, Aspersa initiates foreplay with some lubricious nibbling and then both partners align their common reproductive openings (located just behind the head).

During courtship, they discharge a hypodermic ‘love dart’ a hollow telum amoris with four longtitudinal blades—into their paramour, to stimulate fertilisation. The penis is everted by blood pressure (causing the horns simultaneously to droop) and mating may continue for 12 hours while a spermatophore is transferred into each opposing vagina.

A fortnight later, clutches of several dozen eggs are laid, enrobed in albumin and resembling microscopic mistletoe berries. The young emerge complete with a miniature shell (the ‘protoconch’) and there is no metamorphic stage: each is born with a house for life.

Snail meat has been eaten since the Stone Age and heliculture was probably an early example of animal domestication. Thousands of tons are now consumed annually across Europe, farmed in escargotières or gathered wild. For the classic dish à la Bourguignonne (tackled with obstetrical-style forceps), the Aspersa is sometimes served up in the shell of its larger cousin Helix pomatia, offering a more capacious vehicle for garlic butter.

These days, many a gastropod features in some fancy gastro-pub recipe, but it was once working men’s food Newcastle’s glass-blowers ate snails to strengthen their lungs and, in the West Country, they were sold under the ghastly sobriquet of ‘wall fish’. Victorian dairymen surreptitiously whisked them into milk to impart a creamier texture and folk remedies included cures for scrofula, consumption and warts.

From Aristotle to Günter Grass, the world according to old Belly Foot has long intrigued writers and thinkers, who have seen it variously as an emblem of determination, independence, fragility or solitude Thom Gunn’s exquisite poem Considering The Snail has its subject’s ‘thin trail of broken white’ reproduced in the track of his own words on the page and Ted Hughes admired them: ‘Slimed as eels, wrinkled as whales/And cold/As dogs’ noses.’

Its tumescent horns and association with the lunar cycle have made the snail a fertility symbol and its habit of withdrawing and reappearing was once a resurrection motif. Artistically, its shelly spiral has inspired everything from childrens’ cartoonish sketches to the architecture of pagodas and the late, large gouaches découpées of Matisse.

The novelist Patricia Highsmith, who wrote two Grand Guignol stories about snails, carried them as pets in her handbag. Now, that is a far cry from Heston’s convoluted porridge.