Land snail facts for kids
Quick facts for kids Land snail |
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| The Helix pomatia snail, also known as the Roman snail, is a type of land snail. It's a bit bigger than the common garden snail. | |
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| A common garden snail (Cornu aspersum) in Israel. | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Groups included | |
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A land snail is a type of snail that lives on land. This is different from sea snails, which live in the ocean, and freshwater snails, which live in rivers and lakes. Land snails are gastropod mollusks that have a shell. Snails without shells are called slugs. Sometimes it's tricky to tell if a snail is truly a land snail, as some can live in both land and water environments.
Land snails are a diverse group. They have evolved to live on land at least ten different times throughout history. Most land snails are called "pulmonates" because they have a lung and breathe air. Other land snails, like those in the Caenogastropoda group, often have a gill and a special "door" called an operculum. Many of these snails live in damp places, like in moss.
Land snails have a strong, muscular foot. They use mucus to help them crawl over rough surfaces. This mucus also keeps their soft bodies from drying out. Like other mollusks, snails have a mantle, which is a special layer of tissue. They also have one or two pairs of tentacles on their head. Inside, they have a radula (a ribbon-like tongue with tiny teeth) and a simple brain.
Many land snails are hermaphrodites. This means they have both male and female reproductive organs. Most of these snails lay groups of eggs in the soil. Tiny snails hatch from these eggs with a small shell. The shell grows in a spiral shape as the snail gets bigger. Most land snail shells coil to the right.
Many animals, both big and small, eat land snails. Humans also eat snails in different cultures around the world. Some places even raise snails on farms for food.
Contents
Exploring the World of Land Snails
What Makes a Land Snail Special?
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Land snails move by gliding on their muscular foot. This foot is covered in tiny hairs called epithelial cilia and lubricated with mucus. Waves of muscle contractions move along the bottom of the foot, pushing the snail forward. You can easily see this movement if a snail crawls on a window. Snails are known for being slow, moving about 1 millimeter per second.
Snails produce mucus to keep their soft bodies from drying out. The mucus also helps them move by reducing friction. It protects them from sharp objects, allowing them to crawl over rough surfaces without injury. The mucus leaves a shiny slime trail behind them, which can be seen for hours.
Snails have a mantle, which is a special tissue layer. It covers all their internal organs. The mantle also creates the snail's shell and helps it grow.
Most mollusks, including land snails, have a shell from when they are very young. When a snail is active, its organs like the lung, heart, and intestines stay inside the shell. Only its head and foot come out. The shell grows as the snail grows. It adds new calcium carbonate material along its open edge. Snails need plenty of calcium in their diet to build strong shells. Without enough calcium, their shells can become thin or cracked. Snails can often repair minor shell damage if their living conditions improve.
Some snails have a gill and can close their shell with a "door" called an operculum. This helps protect them when they pull into their shells.
Land snails come in many sizes. The largest living species is the giant African snail (Achatina achatina). It can grow up to 30 cm long. Some Caucasian snails can have shells over 6 cm wide. On the other hand, Angustopila psammion is one of the smallest, with a shell less than 1 millimeter wide.
Most land snails have one or two pairs of tentacles on their heads. In many land snails, the eyes are on the upper pair of tentacles, often called 'eye stalks'. The lower pair of tentacles helps them smell. Both sets of tentacles can be pulled back into the snail's head.
How Snails Eat and Think
A snail uses its radula to break up food. The radula is like a tiny ribbon with rows of microscopic teeth. The snail scrapes food with it, then moves the food into its digestive tract. If it's very quiet, you might hear a large snail "crunching" its food as the radula works.
A snail's simple brain is made of groups of nerve cells called ganglia. This brain is much simpler than those of mammals or birds. However, snails can still learn and remember things.
How Snails Breathe and Stay Safe
Snails breathe using a lung or gills. Oxygen is carried in their blood by a pigment called hemocyanin. Oxygen goes into the blood, and carbon dioxide leaves it, through tiny blood vessels called capillaries. A special muscle valve controls the opening and closing of the lung. This valve helps the snail breathe and also prevents it from losing too much water or drowning.
A Snail's Growing Shell
A snail's calcium carbonate shell grows as the snail gets bigger. The mantle secretes new shell material along the edge of the shell's opening. This means the center of the spiral was formed when the snail was young. The outer parts were made as the snail got older. When a snail reaches its full adult size, it might build a thicker edge around the shell opening. Then, it stops growing and starts to reproduce.
A snail's shell forms a logarithmic spiral. Most snail shells coil to the right, which is called dextral. If you hold the shell with the tip pointing up, the spiral goes clockwise.
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A snail with a right-coiling shell.
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A left-coiling snail from western India.
Hibernation and Estivation
Some snails hibernate during winter, usually from October to April in the Northern Hemisphere. They might also estivate (go into a dormant state) during hot, dry summers. To stay moist during these times, a snail seals its shell opening with a dry layer of mucus called an epiphragm.
The Life Cycle of Land Snails
Most land snails are hermaphrodites. This means they have all the reproductive organs of both sexes. They can produce both sperm and eggs. However, a few groups, like the Pomatiidae, have separate male and female snails. The age when snails become ready to reproduce varies, from 6 weeks to 5 years. Bad environmental conditions can sometimes delay this.
Most air-breathing land snails perform special courtship behaviors before mating. This courtship can last for several hours. In some snail families, one or more "love darts" are used to interact with their partner before mating.
Pulmonate land snails are good at reproducing. They mate in pairs and fertilize each other's eggs internally. They do this through a reproductive opening near the front of their body. After fertilization, the eggs develop. Each group of eggs can have up to 100 eggs.
Garden snails usually bury their eggs in shallow soil. They prefer warm, damp weather and dig about 5 to 10 cm deep with their foot. Egg sizes vary by species. For example, grove snail eggs are about 3 mm wide, while Giant African Land Snail eggs can be 6 mm wide. After 2 to 4 weeks in good weather, the eggs hatch, and young snails emerge. Snails can lay eggs as often as once a month.
Sometimes, different snail species can create hybrid offspring, though this is rare in the wild. Some species can also self-fertilize, meaning they can reproduce without a partner.
How Long Do Snails Live?
Many land snail species live for about a year. Others live 2 or 3 years. Some larger species can live over 10 years in the wild. For example, Roman snails (Helix pomatia) often live for 10 years in nature. In captivity, snails can live much longer, sometimes up to 25 years for H. pomatia.
What Do Snails Eat?
Snails eat many different foods in the wild. Most land snails are herbivorous, meaning they eat plants. Their diet can include leaves, stems, soft bark, fruit, vegetables, fungi, and algae. Some snails have special bacteria in their bodies that help them digest tough plant materials like cellulose.
However, some snail species are carnivorous, meaning they eat other animals. The genus Powelliphanta includes the largest carnivorous snails in the world, found in New Zealand. Other predatory snail families include the Spiraxidae and Rhytididae. Because some snails eat garden plants and farm crops, they are sometimes seen as pests.
Who Eats Snails?
Many animals, both big and small, hunt and eat snails. Some birds, like the song thrush, break snail shells by hitting them against a hard rock. This exposes the soft snail inside. Other predators, like some frogs, simply swallow the snail whole, shell and all.
Some carnivorous snails, like the decollate snail and the rosy wolf snail, also eat other land snails. These predatory snails are sometimes used to control pest snails. However, if they escape into the wild, they can harm native snail species.
To protect themselves, land snails pull their soft bodies into their shells when resting. Some even bury themselves in the ground. Snails have many natural predators, including thrushes, hedgehogs, and certain snakes. Invertebrate predators include other snails, ground beetles, leeches, and even some caterpillars.
Sometimes, snails can be affected by tiny organisms called parasites. For example, the marsh snail Succinea putris can be infected by a tiny flatworm. These flatworms make the snail's eye stalks swell up. Birds are attracted to these swollen eye stalks and eat them, which helps the flatworm complete its life cycle.
Human activities also pose dangers to snails. Pollution and habitat destruction have caused many snail species to disappear in recent years.
Snails and Their Environment
Snails can easily lose moisture from their bodies. They are most active at night and after it rains. During dry or unfavorable conditions, a snail stays inside its shell. It usually hides under rocks or other safe places to avoid predators. In dry climates, snails often gather near water sources, even artificial ones like air conditioner outlets.
Snails as Food for Humans
People have eaten land snails for thousands of years. Evidence of snail eating has been found in ancient sites in North Africa and the Mediterranean region, dating back over 12,000 years. Snail eggs, sometimes called snail caviar, are also a special food that is becoming more popular.
Snails are a good source of nutrients. They are rich in calcium and contain vitamin B1 and E. They also have important amino acids and are low in calories and fat.
It's very important that any snails eaten by humans are cooked thoroughly. This makes sure they are safe to eat and don't carry any tiny organisms that could make people sick. The practice of farming snails is called heliciculture. Snail farms have introduced some species to new parts of the world, where they have sometimes become invasive species.
Snail Dishes Around the World
Snails in Africa
In parts of West Africa, especially Ghana, snails are a popular food. The Ghana tiger snail (Achatina achatina) is one of the largest snails in the world. In Nigeria, snails are called "igbin" by the Yoruba people and "Ejuna" or "Eju" by the Igbo people. In Cameroon, snails are a delicacy, often eaten cooked with spices or with a dish called 'eru'.
In northern Morocco, small snails are eaten as snacks in a spicy soup. This recipe is similar to those found in southern Spain.
Snails in Europe
Snails are eaten in several European countries, just as they were in the Roman Empire. Three main species from the family Helicidae are commonly eaten:
- Helix pomatia, or the edible snail, is often prepared in its shell with parsley butter. These snails are typically found in Burgundy, France, and are known as l'Escargot de Bourgogne.
- Helix lucorum is found in the Eastern Mediterranean and is eaten in Greece and parts of Georgia.
- Cornu aspersum, also known as the European brown snail, is cooked in many ways. It is found in Mediterranean countries and along the French Atlantic coast.
Snails are a delicacy in French cuisine, where they are called escargots. In 2014, there were 191 farms producing escargots in France. Before cooking, snails are often kept for a period to cleanse their systems.
Snails are also popular in Portuguese cuisine, called caracóis. They are often served in snack houses and taverns. They are usually stewed with ingredients like white wine, garlic, piri piri, and oregano. Larger snails, called caracoletas, are often grilled with butter sauce. Portugal consumes about 4,000 tonnes of snails each year.
Traditional Spanish cuisine also uses snails, called "caracoles" in Spanish. Several species are eaten, including Cornu aspersum and Theba pisana. Snails are very popular in Andalusia, Valencia, and Catalonia. There are even snail festivals, like the "L'Aplec del Caragol" in Lleida, which attracts many visitors.
Smaller snails are often cooked in spicy sauces or soups and eaten as an appetizer. Larger ones are used in more complex dishes, like "arroz con conejo y caracoles" (rice with snails and rabbit meat).
In Greece, snails are popular, especially on the island of Crete. They are sold alive in supermarkets. They can be boiled with vinegar or cooked in a casserole with tomato and potatoes. A traditional Cretan dish is Kohli Bourbouristi, which is fried snails with olive oil, salt, vinegar, and rosemary.
Snails, called karaoloi, are also found on Cypriot taverna menus. In Sicily, snails (babbaluci) are a popular dish, usually boiled and served with tomato sauce or oil and garlic. Snails are also enjoyed in other Italian regions.
On the Mediterranean island of Malta, snails (bebbux) are prepared similarly to the Sicilian style. In southwestern Germany, there is a regional soup specialty with snails and herbs.
Heliciculture is the farming of snails. Some species, like the Roman snail, are protected in the wild in Europe. However, they are raised on snail farms.
While not a widespread tradition, common garden snails (Cornu aspersum) were eaten in the Southwick area of Sunderland, North East England. This tradition was introduced by French glass workers in the 19th century. People collected hibernating snails from quarries and railway walls. "Snail suppers" were a feature of local pubs until at least the 1970s.
Snails in Oceania
In New Caledonia, the Placostylus fibratus snail, called bulime, is a highly valued food. It is farmed locally and often served in restaurants with garlic butter, in the French style.
Protecting Plants from Snails
To control snails that might harm plants, people use different methods. Metaldehyde and iron phosphate are substances that can be used to get rid of snails. Copper can also be used as a barrier material. Snails don't like to crawl over copper because it gives them a mild electric shock.
See Also
- Cretan cuisine
- Freshwater snail
- Sea slug
- Sea snail
- Slug
- Snail slime
- Terrestrial mollusc
