# Snail — Facts, Threats & Conservation *Class Gastropoda (shelled members) — tens of thousands of land, freshwater and marine species* > Snails are shelled gastropod molluscs living on land, in fresh water and in the sea; they move on a single muscular foot, feed with a toothed radula, and land snails account for more documented modern extinctions than any other animal group. **IUCN status:** Group page — includes some of the most extinction-prone animals on record · **WARN range:** Worldwide — land, freshwater and marine, Greatest land-snail diversity on oceanic islands and limestone hills ## Quick facts | Fact | Value | | --- | --- | | Habitat | Land, fresh water and marine | | Locomotion | Muscular waves on a single foot, on mucus | | Feeding | Radula — a ribbon of thousands of teeth | | Shell | Calcium carbonate, secreted by the mantle | | Dormancy | Aestivation and hibernation behind an epiphragm | | Conservation | ~40% of documented modern animal extinctions | ## Scientific classification - **Kingdom:** Animalia - **Phylum:** Mollusca - **Class:** Gastropoda - **Note:** 'Snail' is a body-form term, not a single taxonomic group - **Familiar species:** Cornu aspersum (garden snail), Helix pomatia (Roman snail) ## Conservation status - **Status:** Varies enormously by species — group page - **Population:** Not applicable at group level - **Trend:** Severe declines and extinctions among island and limestone endemics - **Assessed:** Assessed species-by-species - **CITES:** Appendix I for Achatinella spp. (Hawaiian tree snails); other listings apply to some marine species - Introduced predators — rats, ants, flatworms and the rosy wolfsnail introduced as failed biological control — are the dominant driver of land snail extinctions. ## Key facts: Snail - Snails and slugs are both gastropods — slugs are essentially snails whose shell has been reduced or lost. - The radula is a toothed ribbon; a garden snail may carry thousands of teeth, continuously replaced. - Most land snails are hermaphrodites, and each individual can produce eggs. - Shells are built from dietary calcium, so snails are scarce on calcium-poor soils. - Molluscs account for a disproportionate share of documented modern extinctions, mostly island land snails. - Slug pellets containing metaldehyde poison predators up the chain; barriers, timing and tolerance work better. ## How a snail is built The shell is secreted by the mantle from calcium carbonate and grows with the animal, adding material at the aperture in a logarithmic spiral. Because the shell is made from dietary calcium, land snails are abundant on chalk and limestone and scarce on acidic, calcium-poor ground. Movement comes from waves of muscular contraction running along the single foot, lubricated by mucus that also seals moisture in and helps the animal cross rough or sharp surfaces. Land snails carry eyes at the tips of the upper tentacles and chemosensory organs on the lower pair; aquatic snails generally have eyes at the tentacle bases. ## The radula Instead of jaws, gastropods feed with a radula — a flexible ribbon carrying rows of chitinous teeth that rasps material into the mouth. Tooth number runs into the thousands in some species, and the ribbon is continuously produced at the back as the front wears away. Radula shape tracks diet, and gastropod diets are extraordinarily varied: algae grazers, leaf eaters, detritivores, filter feeders, and predators. Cone snails have modified the radula into a hollow, harpoon-like tooth used to inject venom into fish — venom now studied intensively for pain medicine. ## Reproduction and dormancy Most land snails are simultaneous hermaphrodites, carrying both male and female organs. Courtship can be elaborate, and in some species includes firing a calcareous 'love dart' into the partner, which improves the sender's sperm survival. After mating, both individuals may lay eggs, usually in a shallow chamber in damp soil. When conditions turn hostile, land snails seal the shell aperture with a mucus membrane — an epiphragm — and go dormant: aestivation in heat and drought, hibernation in cold. Some species can hold that state for months or, in desert species, far longer. ## The extinction record nobody talks about Land snails are extremely prone to becoming narrow-range endemics: poor dispersers, tied to specific microhabitats, isolated on islands and limestone hills. That makes them exceptionally vulnerable. Introduced rats, ants and flatworms, habitat clearance, limestone quarrying and — notoriously — the deliberate introduction of the predatory rosy wolfsnail as a failed biological control, have driven very large numbers of species to extinction, particularly in Hawai'i and French Polynesia. Molluscs make up roughly 40% of documented animal extinctions since 1500, overwhelmingly land snails, and the true figure is almost certainly higher because many species were never described before disappearing. A handful of Partula tree snails survive only because captive populations were established in zoos before their islands were overrun. ## What WARN does WARN publishes free, sourced species education across the whole of animal life. The animals that carry the heaviest extinction burden are rarely the ones that attract attention, and land snails are the clearest example: enormous losses, almost no public profile, and a well-documented history of harm caused by badly assessed biological control. If this guide helps you understand wildlife and the pressures it faces, a gift to WARN supports habitat protection and free public education in our partner countries. ## Frequently asked questions: Snail ### What is the difference between a snail and a slug? Both are gastropod molluscs. Snails carry an external coiled shell they can withdraw into; slugs have lost the external shell or reduced it to a small internal plate. Slugs are not a single group — shell loss has evolved repeatedly in different snail lineages. ### Do snails have teeth? Yes, thousands of them, on a ribbon-like structure called the radula rather than in jaws. The teeth rasp food into the mouth and are continuously replaced as they wear down. ### How long do snails live? Garden snails typically live two to five years. Some larger land snails reach ten or more, and certain deep-sea and freshwater species live considerably longer. ### Are snails male or female? Most land snails are simultaneous hermaphrodites with both male and female reproductive organs, so two mating snails can each go on to lay eggs. Many marine snails have separate sexes. ### Are snails dangerous? Snails are not generally dangerous to people. Snails are shelled gastropod molluscs living on land, in fresh water and in the sea; they move on a single muscular foot, feed with a toothed radula, and land snails account for more documented modern extinctions than any other animal group. Give wild individuals space and do not corner or handle them. ### How big is a snail? Snails are shelled gastropod molluscs living on land, in fresh water and in the sea; they move on a single muscular foot, feed with a toothed radula, and land snails account for more documented modern extinctions than any other animal group. ## Sources - [IUCN Red List](https://www.iucnredlist.org/) - [CITES Appendices](https://cites.org/eng/app/appendices.php) --- Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/snail