Snails are the only mollusks that live not only in water but also on land. On land, they crawl slowly, leaving a trail of slime to slide on. Land snails can be roughly divided into slugs and shell snails. In Switzerland, they are called house snails because they carry a small house around with them.
Snails are found all over the world, even in the Arctic and Antarctic seas. They can be smaller than a millimeter, but also very large: one species of snail in the Indian Ocean even reaches a length of up to 90 centimeters.
The individual snail species are very different from each other. The following applies to all: The body consists of the head, the foot, the viscera, and the mantle, as with all mollusks. Everything else can be very different. Therefore, this article mainly describes examples.
What do snail bodies look like?
Shell snails carry a shell on their back. It corresponds to the shell of the mussels. The visceral sac always remains in the shell. You can also withdraw your foot there. They do this when they are dry and seal the opening with a thick layer of mucus. The land snails also do this to survive the winter better.
In the case of slugs, the shell has disappeared in the course of evolution. All that remained was a strong skin called a “mantle”. The visceral sac lies beneath the mantle.
Head and foot look like one piece. All snails have antennae, but only a few have eyes. The scientists call them “cup eyes”. These are depressions in the skin in the shape of a cup. There are up to 30 visual cells on its surface. The light always only falls on a part of these photoreceptor cells. This allows the snail to recognize where it is lighter or darker. The eyes sit like black dots on top of the tentacles.
All snails are deaf, but at least the land snails can smell very well. However, they don’t have a nose, instead, they have individual cells that allow them to smell. They are mainly located on the front half of the body.
Snails have a heart and some veins. Your blood mixes with another body fluid to form hemolymph. They say “hemolums”. It flows freely throughout the body. Most land snails breathe with simple lungs. All sea slugs breathe with gills. Snails have an esophagus, a stomach, an intestine with an exit, a liver, and kidneys.
How do snails live?
Land snails move very slowly. They put a slime carpet under the foot on which they can slide. This slime carpet also protects them from sharp surfaces. In order to move forward, they lift the foot slightly at the back so that a fold is created like in a carpet. They then let this fold move forward to the head. Then the next fold follows. You can observe this very nicely by letting a snail crawl over a glass plate.
Land snails do not tolerate drought or even sun. They are therefore particularly active at dusk, at night, or when it rains. When the sun is shining, they retreat to the shade so that they don’t dry up.
Land snails spend the winter in crevices in the ground. They go as deep as possible because the ground there freezes little. Shell snails retreat into their shell and seal the entrance with a thick layer of mucus, which then hardens.
Snails can neither flee nor defend themselves, so they have many enemies: hedgehogs, moles, shrews, frogs, toads, blindworms, salamanders, grass snakes, and many birds like to eat snails. They provide a lot of protein, similar to fish. In times of hunger, there are many more animals that would rather eat snails than nothing at all, such as foxes.
How do snails feed?
No snail has real teeth, but all have a rasping tongue. The land snails use it to scrape off parts of the plant like a file. What they put in their mouths is fine enough that they can swallow and digest it.
Snails are the terror of gardeners. They eat everything that is tender on the plants first. Then they also attack the stalks. While salads can disappear in one night. There are also flowers that they love very much, for example, the marigolds, which are also called marigolds. They smell strong and attract the snails magically.
There are also snails that eat carrion, i.e. dead animals. These snails have small rasp teeth. The cone snail from the sea, for example, has a few small teeth like harpoons with which it injects poison into its prey. This paralyzes the prey and the snail can consume it.
How do snails reproduce?
Most snails are bisexual, so there are males and females. So are all sea snails and some freshwater snails. Their hatchlings develop as larvae that swim freely in the water.
The terrestrial snails are hermaphrodites. They include Roman snails and red slugs, which are also called horse snails in Switzerland. With these snails, each animal is male and female at the same time.
Hermaphrodites are called “hermaphrodites” in science. During mating, one animal first slides its penis into the other’s vagina and releases its sperm, then they switch roles. Both snails then carry fertilized egg cells, which develop into eggs.
Each animal then digs a small hole in the ground and lays the eggs in it. These develop independently until the little snail’s hatch. They are immediately independent and look for their own food.
Do snails harm or benefit nature and humans?
Nature knows no pests. Everything benefits the cycle of life. Snails and their eggs serve as food for many creatures. That is why snails are also important for nature.
When people plant fields or gardens, they interfere with nature. There the snails multiply very quickly because they find a lot of food. In addition, the enemies of the snails are often missing in large plantations because they can no longer find natural habitats. Then the snails get the upper hand and eat everything bare.
Farmers and gardeners must therefore do something against snail plagues. Some gardeners take advantage of the fact that snails need moisture: they lay out boards or bricks for the snails to crawl under. The gardeners then collect them there.
You can also get animals that eat the snails: Various quails or ducks have proven themselves so far. But it is also useful to design the garden in such a way that hedgehogs or slow worms, for example, feel comfortable in it.
Very effective is Snail Venom. The problem is that the poison also gets into the environment in other ways or that, for example, slowworms eat snails that have just swallowed snail venom. The blind worms can then also die from this, and the plague of snails will become even greater.
Who eats snails?
Already in ancient Rome, there were recipes for snails. They were considered a delicacy, a special treat. In the Middle Ages, a pope declared that snail meat was lean: this meant that monks could eat it even during Lent. Later, snails were considered food for poor people.
That changed again in the 1800s. Snails are very popular, especially in France. They are a very healthy food because they contain hardly any fat but valuable proteins and minerals. However, they become less healthy if they are boiled and butter is added.
Today, snails are usually eaten as a delicacy. This snail species is protected and may not be collected in the wild. However, it is allowed to breed them on snail farms.