The name snail applies to most members of the molluscan class Gastropoda that have coiled shells .These snails are of herbivorous nature. Other gastropods, which lack a conspicuous shell, are commonly called slugs, and are scattered throughout groups that primarily include snails. Snails are found in freshwater, marine, and terrestrial environments. While most people are familiar with only terrestrial snails, the majority of snails are not terrestrial. Snails with lungs belong to the group Pulmonata, while those with gills form a paraphyletic group.

Stretching snails: Snails move like earthworms by alternating body contractions with stretching, with a proverbially low speed. They produce mucus in order to aid locomotion by reducing friction. The mucus also reduces the snail's risk of injury and helps keep away potentially dangerous insects like ants. When retracted into their shells, snails secrete a special type of mucus which dries to cover the entrance of their shells with a 'trapdoor' like structure called an operculum. This is similar to some slug species which build a shell-like object below their upper skin to prevent drying out. The operculum of some snails has a pleasant scent when burned, so it is sometimes used as an ingredient in incense.

Shell hibernation: In winter or in dry seasons, some snail species hibernate in their shells by building the operculum, which is for protection while hibernating and which is destroyed in spring or when their surroundings becomes wetter. Some species gather and hibernate in groups while others bury themselves before hibernating.

All shapes and sizes: Snails come in a range of sizes. The largest land snail is the Giant African Snail (Achatina achatina; Family Achatinidae), which can measure up to 30 cm. Pomacea maculata (Family Ampullariidae), or Giant Apple Snail is the largest freshwater snail, with its size reaching 15 cm diameter and over 600 g weight. The biggest of all snails is Syrinx aruanus, a marine species living in Australia.

Snail grows=shell grows: As the snail grows, so do their shells. A snail will close off a section of its shell and add a new chamber as it grows, each chamber being larger than the previous one by a constant factor. As a result, the shells forms a logarithmic spiral. At some point, the snail builds a lip around the opening of the shell, stops growing, and begins reproducing.

Calcium-essential to a healthy diet: Snail shells and egg casings are made up of primarily calcium carbonate like other mollusk's shells. Because of this, they require a decent amount of calcium in their diet and watery environment to produce a strong shell. A lack of calcium, or a fluctuation in pH level in their surroundings, would likely cause their shells to be thin, crack, or have holes. Usually a snail can repair its shell damage over time if their living conditions improve, but some damage could be severe enough to be fatal for the snail. Snails hibernate during the winter (typically October through April). They may also hibernate in the summer in drought conditions when it is known as aestivation.

Hemaphrodites: Some snails are hermaphrodites, producing both spermatozoa and ova. Others, such as Apple Snails, are either male or female. Prolific breeders, snails in pairs inseminate each other to internally fertilize their ova. Each brood may consist of up to 100 eggs.

Many predators: Snails have many natural predators, including decollate snails, ground beetles, snakes, toads, turtles, and birds like chickens, ducks and geese, and even a predatory caterpillar.

Danger- humans!! Humans also pose great dangers to snails. Besides the obvious threat of stepping on them or putting salt on the fleshy body part, water pollution and acid rain destroy their shells and poison them, causing many species of snails to become extinct. In addition, snails are used as human food (often known as escargot) in Europe, Asia and Africa.

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