Snails are a group of shelled mollusks, with species found in many habitats, such as freshwater, sea and land. Land snails, although better known than other types, represent a small group. Marine snails are the most numerous and biodiverse group. However, all snail species need oxygen, food, water and adequate temperature and humidity to live. Present in human life since ancient times, snails are garden pests, but are also farmed as gastronomic delicacies.
Snails are omnivorous animals, which means they can eat food from plant and animal sources. Snails can feed on a variety of materials, such as decomposing plants and invertebrates, and any type of leaf or algae. However, different snail species can have distinct food preferences. The giant African land snails (Achatina fulica) -- which are popular pets in some countries but also serious agricultural plagues and illegal to keep in the U.S. -- can eat any food crop, including lettuce, cucumber and cabbage. The wood snail feeds mainly on decaying organic matter, nettles and buttercups, while water snails eat small invertebrates and algae.
Like most animal species, snails need oxygen to survive. Most land snails, and some marine and freshwater species, have a single lung, where the exchanges between oxygen and carbon dioxide occur. Aquatic species have to come to the surface to breathe, in order to take the atmospheric oxygen. Pond snails, bladder snails, ram's horn snails, the common land snail and freshwater limpets are examples of snails that breathe through lungs. Some snails, such as water nerites, bithynias and mud snails, have gills instead of lungs, and can only take the oxygen dissolved in the water.
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Like most living creatures, both land and water snail species need to drink water to survive. Land snails drink from small puddles formed on leaves or on the ground, but they also get their water from the juicy leaves they eat. Marine species take saltwater when feeding, but have an excretory mechanism to eliminate excessive salt quantities they ingest.
Adequate Temperatures and Humidity
Optimum temperatures vary according to species, but most land snails prefer warm temperatures from 65 to 80 degrees Fahrenheit and high-humidity environments. Sphincterochila boissieri, which is found in Egypt and Israel, and can withstand temperatures of up to 120 degrees Fahrenheit. However, this species lives in a dormant state for most of the time, becoming active only after the rain. Some species of the genera Arion and Deroceras are found in temperate climates, but are also adapted to live in polar climates.