Snails
Webpages concerning "Snails"
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Wikipedia-Article "Snails"
- Snail also refers to a chess engine; see Snail (chess) as well as a power source for a rotary snowplow.
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The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. 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 belong to the Paraphyletic group.
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Physical characteristics
Snails move like worms 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 secrets 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 taken and used as incense.
In winter or in dry seasons, some snail species hibernate in their shells by building the operculum, which they build only for the purpose of protection while hibernating and are destroyed in spring or when their surroundings becomes wetter. Some species would gather and hibernate in groups while others would bury themselves before hibernating.
Snails come in a range of different 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. Shell lengths up to 1 m have been reported.
Snail shells, like those of the Nautilus, are one example of the appearance of the phi, the golden ratio, in nature. Patterns on shells of certain sea snails (Conus, Cymbiola) are formed by biological version of cellular automata.
As the snail grows, so do their shells. A snail will close off a section of their shell and add a new chamber as it grows larger, each chamber being larger than the previous one by a constant factor. As a result, the shells forms a logarithmic spiral. At some point, a snail would build a lip around the opening of their shell, and when that happens, they would stop growing and start spending their energy and effort reproducing.
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 enviroment to produce a strong shell. A lack of calcium, or if the pH level of their surrounding starts fluctuating, 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.
Habitat
As one of the largest classes of animals, snails can be found throughout the world. They are found in freshwater, marine, and terrestrial environments. The majority of the world's snails live in the oceans and new species are being discovered regularly. Terrestrial snails prefer damp areas around vegetation which they can use for cover during the day. Certain snails would hibernate during dry weather periods by hiding in their shells for extended periods of time.
Diet
A snail's diet varies by species. Terrestrial snails such as garden snails generally eat young plant shoots or bark, algea, moss, or decaying vegetative matter. Carnivorous snails, such as the Decollate Snail feed on other snails. Snails eat by using their radula, or scraping tongue, to shear their food.
Reproduction
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.
Garden snails bury their eggs in shallow topsoil primarily while the weather is warm and damp. After 2 to 4 weeks of favorable weather, these eggs hatch and the young emerge. Snails may lay eggs as often as once a month.
Predators
Snails have many natural predators, including ground beetles, snakes, toads, turtles, and birds like chickens, ducks and geese, and even a predatory caterpillar.
Humans also pose great dangers to snails. Water pollution and acid rain destroys their shells and poisons them, causing many species of snails to go extinct. In addition, snails are widely used as human food (often known as escargot) in Europe, Asia and Africa.
Lifespan
The lifespan of snails varies from species to species. In the wild, Achatinidae snails live around 5 to 7 years and Helix snails live about 2 to 3 years. Aquatic Apple Snails live only a year or so. Most deaths are due to predators or parasites. As noted at the following address, snails have lived beyond this lifespan: "more than 30 years"
http://www.weichtiere.at/Mollusks/Schnecken/weinberg.html
Control (Garden Pests)
Terrestrial snails and slugs are generally both migratory and nocturnal, thus difficult to control. Common methods of control include shallow dishes filled with beer, and the use of molluscicides.
A more crude, if not effective approach is to sprinkle salt on snails and slugs, which dehydrates their bodies and poisons them. However, this is not generally recommended as too much salt can be harmful to gardening plants.
Snails as Food
Snails are eaten as food in some parts of the world. Although escargot is the French word for "snail", escargot on an English menu is generally reserved for snails prepared with traditional French recipes.
In Europe, three species are ordinarily eaten:
- Helix pomatia, the Burgundy Snail, prepared in its shell, with parsley butter.
- Typical size: 40 to 55 mm for an adult weight of 25 to 45 g.
- Typically found: in Burgundy.
- Helix aspersa :
- Helix aspersa aspersa also known as the European brown snail,
is cooked in many different ways, according to different local traditions.
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- Typical size: 28 to 35 mm for an adult weight of 7 to 15 g.
- Typically found: Mediterranean countries (Europe and North Africa) and the French Atlantic coast.
- Helix aspersa maxima .
- Typical size 40 to 45 mm for an average weight of 20 to 30 g.
- Typically found: in North Africa.
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Achatina fulica, a giant African snail, is sliced and canned and passed off on some consumers as escargot.
Snails are also popular in Portugal, where they are called "caracóis" (Portuguese for "snails"), and served in cheap snack houses and taverns, usually boiled with garlic.
Hélicicultures are snail farms. http://www.weichtiere.at/Mollusks/Schnecken/weinberg.html found at the previous link, "In nature they almost everywhere are put under protection (at least the Roman snail must not be collected any more), but especially the Roman snail and the garden snail (Cornu aspersum) are cultivated on snail farms (Hélicicultures). "
http://www.weichtiere.at/Mollusks/Schnecken/land/weinberg/zucht.html
Various snail species are also eaten in asian cuisines as well.
Trivia
In addition to being a common metaphor for a slow person, the snail is traditionally considered in many countries to predict the weather with its behaviour. In Finland this has led to a rhyme, where the snail is asked to show his tentacles. If the snail wears his "horns" high, tomorrow will be fine weather. In Sweden the following is a childrens song.
Lilla snigel
Lilla snigel, akta dej,
akta dej, akta dej,
annars tar jag dej.
Roughly translated it says something like: Little snail watch out or I'll grab you.
Snail is also the name of the Ultimate Frisbee team for the State University of New York at Geneseo.
A snail can withstand the force of air at over 75 Mph (120 km/h) whilst still being able to move across the bonnet of the moving vehicle at the same time.
External links
- Snail eating
- Brown garden snail
- Molluscs
- Kiddyhouse.com page on snails
- Snails as pets
- The trail of the snail
- AppleSnail.Net
- Lilla snigel
