|A grapewine snail (Helix pomatia)|
Snails and slugs which breath with a kind of lung are members of a group, the Pulmonata, which was a well-known order in traditional taxonomy. Their fossil records extends back into the Carboniferous period.
However, the Pulmonata was found to be polyphyletic in a molecular study. What this means is that, in the course of evolution, the same life-style evolved in a number of different lines. Therefore the pulmonates are polyphyletic, and the Pulmonata is no longer an official term in biological classification.
The term "snail" is also sometimes used for aquatic snail-like gastropods, which usually have gills. Actually, most snail species are marine snails: they have much greater diversity and a greater biomass. Numerous kinds of snail can also be found in fresh water.
Close relatives of the snails are the slugs, which are basically snails without shells. Both slugs and snails are numerous and successful on land. Most land snails and slugs are herbivorous. Aquatic snails and slugs are usually omnivores or predatory carnivores.
The biggest snail is the giant African snail. Their foot is up to 35 cm long. The fastest snail is the Helix aspersa. It can reach speeds up to 0.03 mph. There are known more than 43000 species of snails all over the world.
Land snails are nocturnal animals and move to food and partners in the late evening or at night. They prefer a damp, but not a wet environment and bury themself up to two weeks in hot and dry phases. Their enemies are birds and mammals like mice and similar predators normally.
There are also many water snails. Some of them live in rivers or freshwater, but most are resident on oceans ground. Ocean snails are colorful, so they can be pink, blue, red, grey, yellow and also with many other colors. The colors protect them, because this colours scare potential enemys away. Water snails are not as active as land snails in general, but they mostly do not distinguish different daytimes. Water snails' most abundant enemies are fishes of prey.
Snails are invertebrates, which are animals with no backbones. The shell on the snail helps protect it, and also reduces the loss of water by evaporation. Shells have many different shapes, sizes, and colours. Snails do not breathe through their mouths, instead they have a breathing hole under their shells.
A snails "foot" is a muscle which allows it to move slowly across the ground. The foot puts out ('exudes') slime, which eases the snail's movement, leaving a trail. Snails can absorb mineral nutrients through their foot by simply sitting on a rock containing it.
The head is attached to the foot. The mouth is like a cheese grater. It is called a radula. It is used for cutting food. On the radula there are little teeth. On the head there are 15 mm stalks. At the end of the stalks are snail’s eyes, though they do not see very well.
Snails are found all over the world. Generally speaking, land snails live on damp habitats. They live in caves and dark places. Snails can be found in dark places such as in a garden under plant's foliage leaves. Some species live in cold places like the Arctic and a few are found in warm places like beaches and deserts.
Some snails are aquatic and live in water. They live in the sea, fish tanks, rivers and oceans. They do not swim in the water because most of the time they stick to rocks.
Land snails eat vegetables and fruits, such as lettuce, carrots, cucumber and apples. Aquatic snails are often carnivorous. Snails use their radula to cut food. The radula is a hard, rough plate in the mouth. Radula teeth are like little pieces of sandpaper. They are good for cutting up plants and if the snail eats meat they are good for tearing the meat apart. Radula teeth look like little fangs.
Many animals eat snails. Fireflies, snakes, beetles, fish, insects, turtles and people eat snails too. To defend themselves, snails pull back into their shells.
Slugs evolved from snails which reduced, and finally lost, their shells. They live in similar habitats.
Images for kids
The use of love darts by the land snail Monachoides vicinus is a form of sexual selection
Snail Facts for Kids. Kiddle Encyclopedia.