Snail

From Wikipedia, the free encyclopedia

iSnails

Roman snail (Helix pomatia)

Scientific classification

Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda

The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. Snails are found in freshwater, marine, and terrestrial environments. Most are of herbivorous nature, though a few land species and many marine species may be omnivores or carnivores. Other gastropods, which lack a conspicuous shell, are commonly called slugs, and are scattered throughout groups that primarily include snails. 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 form a paraphyletic group.

1 Physical characteristics
2 Hibernation/Estivation
3 Reproduction
4 Predators
5 Lifespan
6 Snails as food
7 Gallery
8 See also
9 As an interjection
10 References
11 External links

[edit] Physical characteristics

Snails move by alternating body contractions with stretching, with a proverbially low speed (1 mm/s is a typical speed for adult helix lucorum ^[1]). They produce mucus in order to aid locomotion by reducing friction. The mucus also reduces the snail's risk of injury (snails can crawl over razor blades without injury, a fact famously alluded to in the movie Apocalypse Now) and helps keep away dangerous insects like ants.

When retracted into their shells, some snails protect themselves with a door-like anatomical structure called an operculum. The operculum of some snails has a pleasant scent when burned, so it is sometimes used as an ingredient in incense.

Snails range greatly in size. The largest land snail is the Giant African Snail or Ghana Tiger 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 a diameter of up to 15 cm and a mass of over 600 g. The biggest of all snails is Syrinx aruanus, an Australian marine species which can grow up to 77.2 cm (30 inches) in length, [1] and 18 kg (40lbs) in weight.[2]

The proportions of snail and nautilus shells are an example of the appearance of the golden ratio in nature. Patterns on shells of certain sea snails (Conus, Cymbiola) are similar to those formed by cellular automata.

As the snail grows, so does its calcium bicarbonate shell. A snail will close off a section of its shell and add a new chamber as it grows, each chamber being larger than the previous one by a constant factor. As a result, the shells forms a logarithmic spiral; most are right-handed, meaning that the whorl is on the right hand side of the shell. At some point, the snail builds a lip around the opening of the shell, stops growing, and begins reproducing.

The shells of snails and other molluscs, and snail egg casings, are primarily made up of calcium carbonate. Because of this, they need calcium in their diet and watery environment to produce a strong shell. A lack of calcium, or low pH in their surroundings, can cause thin, cracked, or perforated shells. Usually a snail can repair damage to its shell over time if its living conditions improve, but severe damage can be fatal.

[edit] Hibernation/Estivation

Some snails hibernate during the winter (typically October through April in the Northern Hemisphere). They may also estivate in the summer in drought conditions. To stay moist during hibernation, a snail seals its shell opening with a dry layer of mucus called an epiphragm.

[edit] Reproduction

Two snails investigate each other prior to mating

All land snails are hermaphrodites, producing both spermatozoa and ova. Others, such as Apple Snails, are either male or female. Prolific breeders, snails inseminate each other in pairs to internally fertilize their ova. Each brood may consist of up to 100 eggs.

Snails have small slits on their necks where fertilization occurs and the eggs develop.

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.

[edit] Predators

Snails have many natural predators, including members of all major vertebrate groups, decollate snails, ground beetles, and even the predatory caterpillar Hyposmocoma molluscivora.

Humans also pose great dangers to snails. Besides the obvious threat of stepping on them or putting salt on the fleshy body part, water pollution and acid rain destroy their shells and poison them, causing many species of snails to become extinct. In addition, snails are used as human food (often known as escargot) in Europe, Asia and Africa.

[edit] 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. On occasions, snails have lived beyond this lifespan, up to 30 years or more.^[2]

[edit] 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 (served in the shell with a garlic & parsley butter).

In Europe, three species, all from the genus Helix, are ordinarily eaten:

Helix pomatia, the Edible 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.
  - 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.

Achatina fulica, the Giant East African Snail, is sliced and canned and passed off on some consumers as escargot. ^{[citation needed]}

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 and oregano. Traditional Spanish cuisine is very fond of snails ("caracoles"), too, consuming several species such as Helix aspersa, Helix punctata, Helix pisana or Helix alonensis among others. Small to medium size varieties are usually cooked in several spicy sauces or even in soups, while the bigger ones may be reserved for other dishes such as the "arroz con conejo y caracoles" (a paella-style rice with snails and rabbit meat, very popular in the inner regions of south-eastern Spain) or the many local versions of gazpacho (also a typical meal of meat and vegetables with pieces of unleavened flour cakes).

In Greece snails are popular in the island of Crete. They are eaten either boiled with vinegar added or cooked in a casserol with tomato, potatoes and squashes. A third cooking method is the χοχλιοί μπουμπουριστοί traditional cretan dish, which consists of fried snails in olive oil with lemon.

In Sicily snails (or babbaluci as they are commonly called in sicilian dialect) are a very popular dish as well. They are usually boiled with salt first, then served with tomato sauce or bare with oil, garlic and parsley.

Hélicicultures are snail farms. "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)."^[2]

Snails (or bebbux as they are called in Maltese are a quite popular dish on the Mediterranean island of Malta.

Various snail species are also eaten in Asian cuisines as well.

[edit] Gallery

Giant East African Snail (Achatina fulica)	Brown garden snail	English garden snail	Two grove snails with banded shells, showing variations in both the number of bands and their colouring.
White-lipped snail (Cepaea hortensis)	Garden Snail photographed in the USA	Two snails mating	White-lipped snail (Cepaea hortensis)
In urban environment: Medford, MA

[edit] See also

Snails in folklore

[edit] As an interjection

The (now disused) interjection "'Snails" is a minced oath whose full form is "God's nails", referring perhaps to the Crucifixion nails rather than to fingernails.