Invertebrates

Snail

Gastropoda · also called land snail, sea snail

Not Evaluated ↓ herbivoreomnivorecarnivore Temperate forest Temperate grassland Ocean

A snail carries its house on its back, moves on a single foot along a road of its own slime, and eats with a tongue that holds thousands of tiny teeth. It belongs to the second-largest class of animals on Earth, and it has a trick few animals can match: when conditions turn against it, it seals the door of its shell and simply stops, sometimes for years, until the rain comes back.

Overview

Snails are the shelled members of the class Gastropoda, which has around 65,000 to 80,000 living species — second only to the insects. There are sea snails throughout the oceans, freshwater snails in rivers and lakes, and land snails almost everywhere on land. All move on a muscular foot and feed with a radula, a rasping tongue-ribbon of tiny teeth. A slug is simply a snail that has lost its shell, which has happened many times independently.

Sealing up

A land snail short of moisture withdraws into its shell and seals the opening with dried mucus, or a limy plate called an epiphragm in desert species, then drops its metabolism and waits — weeks, months, or years — until conditions improve.

Odd love lives

Most land snails are hermaphrodites, both sexes at once, and mate by exchanging sperm — in some species after firing a sharp calcareous “love dart” carrying a hormone that improves the shooter’s paternity.

Delicacy and pest

The Roman and garden snails are farmed as escargot, while the introduced giant African land snail is one of the world’s most damaging invasive species, eating hundreds of crops and carrying a parasite that causes a form of meningitis.

Status

Snails as a class are Not Evaluated, trend decreasing. Garden species are abundant, but land snails have suffered more recorded extinctions than any other animal group — the Pacific island tree snails of Hawaii and French Polynesia were largely wiped out by introduced predatory snails and rats, and many narrow-range species are threatened by habitat loss and invaders.

Snail: common questions

What is the difference between a snail and a slug?

Both are gastropod molluscs, and the main visible difference is the shell. A snail has a coiled external shell large enough to withdraw its whole body into, while a slug has no shell, a very small one, or an internal remnant hidden under the skin. Slugs have evolved from snails many separate times, in land, freshwater, and marine lineages, generally where a big shell is more of a burden than a benefit, for example in animals that squeeze through tight spaces or where calcium for shell-building is scarce. In every other respect, the muscular foot, the slime trail, the radula, the tentacles with eyes, snails and slugs are built the same way.

How do snails move, and why the slime?

A snail glides on a single large muscular foot, sending waves of muscle contraction from tail to head along its underside, each wave pushing a small section of the animal forward. The mucus it lays down is not just lubrication; it is a remarkable material that behaves as a solid until enough force is applied, then flows, which lets the snail get traction to move and also cling upside down or climb a vertical pane of glass. The slime also seals in moisture, carries scent trails that other snails follow, and can gum up the jaws of an attacking beetle or ant.

How long can a snail survive without water or food?

Longer than almost any other soft-bodied animal. A land snail short of moisture pulls into its shell and seals the opening with a dried mucus membrane, or a firmer epiphragm in the driest-country species, then lowers its metabolism to a trickle and becomes dormant, a state called estivation in summer and hibernation in winter. In this condition a snail can survive for months routinely, and desert species have been recorded reviving after one to several years sealed in their shells, including a famous museum specimen that came back to life after being glued to a display card for four years.

Are snails dangerous to people?

Most are entirely harmless, but a few carry real risks. The giant African land snail and some freshwater snails can host the rat lungworm parasite, which can infect a person who eats a raw or undercooked snail, or unwashed produce a snail has crawled over, and cause eosinophilic meningitis. Freshwater snails in parts of Africa, Asia, and South America are the intermediate hosts of the flukes that cause schistosomiasis, a major human disease, though the snail itself does not bite or infect directly. And the marine cone snails deliver a venomous sting through a harpoon-like tooth that, in the fish-hunting species, can be dangerous or fatal to a person who handles the live shell.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Gastropoda
Diet: Mostly plants, algae, fungi, lichen, and decaying matter scraped up with the radula, though many aquatic and some land snails are predators of worms, other snails, and even small fish, and the marine cone snails hunt fish and worms with a venomous harpoon tooth
A tongue covered in thousands of teeth: A snail feeds with a radula, a flexible ribbon in the mouth bearing rows of tiny hard teeth, sometimes tens of thousands of them, that it works back and forth like a rasp to scrape or drill food, wearing the teeth down at the front while new rows grow at the back
Snails and slugs are the same class: Gastropoda contains around 65,000 to 80,000 living species, making it the second largest class of animals after the insects, and a slug is essentially a snail that has lost or greatly reduced its shell, a change that has happened many times independently
Sealing up to survive: A land snail withdraws into its shell and secretes a mucus door, and in dry or cold conditions it can seal the opening with a thicker membrane or a limy plate called an epiphragm, then drop its metabolism and wait, dormant, for weeks, months, or in extreme cases years until moisture returns
Most land snails are hermaphrodites: A typical land snail is both male and female at once, and two snails mate by exchanging sperm, in some species after firing a sharp calcareous love dart into each other, a structure that delivers a hormone improving the shooter's chances of fathering the eggs
They carry their home and can right themselves: The shell grows with the animal, coiled in a spiral around a central column, almost always right-handed, and provides protection, water storage, and a mineral reserve, and a snail flipped onto its back can slowly extend its foot and lever itself upright
Both a delicacy and a serious pest: The Roman or Burgundy snail and the garden snail are farmed and eaten as escargot, while the introduced giant African land snail is one of the world's most damaging invasive species, eating hundreds of crop plants and carrying a parasite that causes a form of meningitis in humans
Range: Almost everywhere on Earth, with sea snails throughout the oceans from the shore to the deep sea and hydrothermal vents, freshwater snails in rivers, lakes, and springs, and land snails from rainforest and mountain to desert, tundra edge, and city gardens, on every continent except the deep interior of Antarctica, and often reaching very high densities in damp calcium-rich habitats.
Conservation status: Not Evaluated ↓ ≈ Not assessed as a class, and while garden and farmland snails are abundant, land snails as a group have suffered more recorded extinctions than any other animal group, with island species especially hard hit, the Pacific island tree snails of Hawaii and French Polynesia largely wiped out by introduced predatory snails and rats, and many narrow-range land and freshwater snails threatened by habitat loss and invasive species in the wild