Large agate snail
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| Large agate snail | ||||||||||||
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Large agate snail |
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| Lissachatina fulica | ||||||||||||
| ( Bowdich , 1822) |
The great agate snail ( Lissachatina fulica ), also called the East African giant snail, belongs to the African giant snail , a family of land snails . With a shell length of up to 20 cm and a body length of up to 30 cm, it is one of the largest land snails in the world.
features
The basic color of the housing is brown to horn-colored and has numerous stripes that mark the growth lines. However, Lissachatina fulica is the species of agate snail whose shell color can vary the most. There are striped, spotted, as well as dark brown and almost black houses. Five to seven color variants are described in agate snail forums. The shape of the case is conical, usually right-handed and tapering to a point. The average length of the case, measured from the apex to the case opening, is between 10 and 12 cm, but specimens with a case length of up to 20 cm were also found. With a case length of 12 cm, the case has a diameter of approximately 5 cm. The soft body is light to dark brown and has a darker eel line .
nutrition
The East African giant snail feeds with the help of a rasping tongue, the radula . The tongue, which is covered with thousands of tiny teeth, is used to take in and chop up food. The snail grates off small pieces of food with the radula. Then she leads them into the throat. A pre-digestion is carried out there with large salivary glands. The food then moves further into the body to the midgut gland, a relatively large organ in the snail. The midgut gland produces digestive secretions and stores the nutrients that could be obtained from food. Furthermore, digestion takes place there by special cells and other cells store the calcium , which they then transport to the desired location via body fluids. The remaining part of the ingested food is excreted through the anus, which uses the opening in the coat. The Achatina fulica is a Omnivor (omnivores). In nature, it feeds mainly on plants, but also takes in available animal proteins in the form of carrion. Mostly she eats vegetables and fruits with little acid, but leaves are often eaten by trees, bushes and smaller plants. Lime is an important part of the snail's diet. It is required to build and maintain the housing. In addition, it is used for the production of eggs and has to be ingested through food.
Reproduction
Snails of the species Lissachatina fulica belong to the group of hermaphrodites , which means that they have both a male and a female sexual organ and can therefore reproduce with any other sexually mature snail of their species. In the case of low population densities, self-fertilization is also possible to preserve the species , but this only occurs very rarely. When two snails of the same size mate, bilateral fertilization occurs. So both animals are fertilized. However, if the snails have significant differences in size, then only the larger one serves as the female. This takes into account the fact that eggs require a lot of space and energy to develop. The snail can store the sperm for up to two years and thus choose the time with the best conditions for its eggs to develop. The mating usually takes place at night and can drag on for several hours. Snails that are ready to mate touch each other's heads and antennae for a long time before sexual intercourse.
Then the genitals, which are located on the right behind the head, are extended and inserted into the partner. 2 to 3 weeks after fertilization, the Lissachatina fulica digs a cave in the ground and lays its eggs there. The clutch size can vary between 100 and 500 eggs depending on size, age and physical condition. After another 2 to 4 weeks, a snail hatches from the 4 mm egg, the size of the shell of which is roughly the size of its egg.
Distribution areas and habitats
Africa
The original range of the agate snail is on the east coast of Africa . It is most widespread in Kenya and Tanzania . There are also many suitable habitats for this species in Madagascar . It inhabits many areas in which there is tropical rainforest and the humidity is very high. It can be found in large quantities in flower gardens and on agricultural land. It has since been introduced to other parts of Africa. The habitat therefore extends over almost all areas that are overgrown by plants and kept moist by rain or artificial irrigation. It is also seldom to be found where there is little rain and there are few plants. The agate snail buries itself in these places for several months and remains dry there, during which it closes its housing opening with a hard and thick layer of lime and slime, which offers optimal protection against drying out. This layer, the epiphragma , is air-permeable and the snail can still breathe through it. When it has rained again after a while outside and plants can grow, the great agate snail sheds the epiphragma and returns to the surface to take in food and possibly reproduce. In nature, the snail is also an intermediate host of pathogens.
Asia
Also, Asia has become the habitat of the Great Agate snail. In the 18th and 19th centuries it was brought to India by colonists' shipping via Mauritius, Réunion and the Seychelles . This took about 100 years. The spreading stopped here for the time being, but after a few years it was discovered as a popular food in Asia. Therefore, many large agate snails were bred and sold in large numbers. The breeding of the albino form was also carried out here. Of course, some animals also managed to break out and they were able to spread undisturbed. In 1910 the Malay Peninsula with the countries Thailand , Myanmar and Malaysia was reached, followed by Borneo in 1928 and then southern China and Japan. The Lissachatina fulica could also partially spread in other parts of Asia, whereby the living conditions in the already mentioned countries and parts of these countries are best suited for reproduction and survival. They also have a good supply of food and rarely have temperatures that are not optimal . An example of this is India, where the average temperature in many parts of the country is between 23 ° C and 28 ° C per year and a humid climate prevails in large parts for 7–8 months of the year. They spend the rest of the year in rigidity underground.
North America
By keeping it as a pet, the great agate snail was also able to spread in the subtropical and tropical regions of North America. The Japanese also brought large agate snails to North America during and after World War II. In the United States, it is most commonly found in the states of Florida , Hawaii , Louisiana, and California , but it also populates other states and some countries in Central America. The above-mentioned states have ideal living conditions for the East African giant snail, because the climate there is both humid and warm and the winters are very mild and almost exclusively have temperatures above freezing point . As in Africa , the agate snail is found in damp places such as gardens, deciduous forests, parks and agricultural areas. Sometimes it even eats the plaster from house walls to meet its lime needs. If it gets too cool in winter or too hot and dry in summer, it falls into a dry state for the duration of the hot or cold period. Most of the eggs are laid in spring, when the conditions for the offspring are best and the death rate is lowest. In nature, the snail is also an intermediate host of pathogens.
Other areas
The great agate snail was able to spread to many other countries due to releases for various reasons and unintentional introduction by humans. The climatic conditions of these countries are predominantly warm with mild winters in which the temperatures rarely drop below 8 ° C. It populates almost exclusively countries with tropical and subtropical climatic zones, which are located in the southern hemisphere. Furthermore, because of its need for air humidity to moisten its mucous membrane, the large agate snail occurs in large numbers in coastal areas and places near the coast, for example on the Spanish Mallorca . Other countries in which the agate snail is native are, for example, Brazil and other South American countries, Greece , Turkey and Indonesia .
status
In many countries the great agate snail is actively controlled by humans as an invasive species . Since a pregnant snail that has survived the extinction measures can form a new colony again , even a regional extinction has not yet succeeded. Measures to eradicate the agate snail include, for example, the use of slug pellets on agricultural land.
Sometimes the rosy wolf snail, Euglandina rosea , which lives predatory and kills its prey with the help of its particularly well-developed radula , was used to combat the large agate snail by releasing it into the wild in affected areas. This was unsuccessful, however, as the rosy wolf snail prefers smaller species such as tree snails and is also responsible for the extinction of several of these species. In addition, it is also used as an intermediate host for the rat lungworm ( Angiostrongylus cantonensis ), which can attack humans by eating snails or their eggs.
Individual evidence
- ↑ Lissachatina fulica (Bowdich, 1822) in MolluscaBase
- ↑ Andreas Leiß: Achatschnecken - Die Familie Achatinidae Berlin 2007, pp. 38–41.
- ↑ Large agate snail - offspring . Agate snail husbandry website.Retrieved June 6, 2014
- ↑ Achatina fulica - Offspring ( Memento from September 11, 2016 in the Internet Archive ). East African giant snail website.Retrieved June 6, 2014
- ↑ a b 100 of the World's Worst Invasive Alien Species . Global Invasive Species Database. Retrieved February 11, 2011.
- ↑ a b Exoticpets
- ↑ a b Hans-Eckard Gruner u. a .: Vol. 3: Invertebrates. In: Urania animal kingdom. 1 edition 1993, pp. 505-507.
- ↑ Achatina fulica (mollusc) - Ecology . issg database. Retrieved June 8, 2014.
- ↑ Achatina fulica (mollusc) - Ecology
