The giant West African snail or banana rasp snail (Archachatina marginata) is a species of air-breathing tropical land snail, a terrestrial pulmonate gastropod mollusk in the family Achatinidae. They can grow up to 20 cm long, and live up to 10 years.
|The shell of Archachatina marginata|
This species occurs in Western Africa (Cameroon to the Democratic Republic of the Congo) and the Caribbean (Martinique). How the species reached Martinique is unknown, but they may have been intentionally introduced as "pets" or by workers returning from West Africa.
The natural spread of this species is very slow; however, unintentional spread by individuals for food and as folk medicine is very common. The USDA routinely checks for the species in the luggage of travelers from West Africa, Nigeria particularly, Ghana, and Cameroon.
This species has not yet become established in the United States, but it is considered to represent a potentially serious threat as a pest, an invasive species that could negatively affect agriculture, natural ecosystems, human health, or commerce. Therefore, this species may be given top national quarantine significance in the United States.
The snail has a bulbous, large, and broad protoconch, with a white or bluish-white columella, parietal wall, and outer lip. The shell of the snail can grow up to 21 cm in height, and 13 cm in diameter. The shell, when magnified, has the appearance of a woven texture.
The snail feeds on a large variety of plants, mainly fruits. Plants included in the snail's diet are bananas, lettuce, peanuts, and peas, some of which are important crops in certain economies. The giant West African snail is one of the worst invasive species in the world and is extremely devastating to any species that it affects. However, the more prevalent problem with the spread of the snail as an invasive species is that it is often a carrier of the parasitic rat lungworm, which causes angiostrongyliasis, which in turn is the most common cause of the eosinophilic meningitis or eosinophilic meningoencephalitis, which is the public health issue that makes the snails' spread to North America problematic. If the snail continues to spread, it could potentially be a problem for the health of people all throughout North America from Cuba to the United States.
Achatinids are nocturnal forest dwellers, but can adapt to disturbed habitats. They prefer concealed habitats, and if overcrowding occurs, they may colonize more open habitats. During periods of high humidity, achatinids are more active, but individuals being found during broad daylight are most likely due to high population density.
Eggs of achatinids are normally laid in the soil, but can be found under leaves or rocks. They produce as many as 40 eggs, which are yellow in color with dark blotches, and their incubation period is about 40 days.
Wild snails eat plants rapidly,[clarification needed] which often leads to property destruction and damage to homes. Snails eat during the day, but they prefer to eat at night. Wild snails are known to eat up to 500 different species of plants. Snails that have become domesticated typically consume food that is high in protein and low in fats. Studies of domesticated snails have shown that poultry droppings have been the most effective meal to both grow and gain weight.
In this organism's nervous system, the two main types of nerves are pallial and visceral. Pallial nerves are the subject of the majority of scientific research. Visceral nerves are split into the main visceral nerve and the rectal visceral nerve. The main visceral nerve is on the snail's back and connects to a large group of nerve cells to transmit information in the body. The rectal visceral nerve starts further down under the main visceral and extends a short length before branching off near the rectum.
Heat can stimulate reactions in the West African snail as a result of the snail's nervous system. The nerves produce warm responsive fibers when the temperature exceeds 25°C and produce cold responsive fibers when the temperature falls below 19°C. The ideal temperature range for this species falls between 13 and 32°C, the thermopreferendum of the species.
- A. m. var. ovum
- A. m. var. suturalis
- A. m. var. egregia
- A. m. var. eduardi
- A. m. var. candefacta
- A. m. var. grevillei
- A. m. var. icterica
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- Let Them Eat Snail: Nutritional Giant Snails Could Address Malnutrition. ScienceDaily (November 20, 2009)
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- Vázquez, Antonio A.; Sánchez, Jorge (2015-04-03). "First record of the invasive land snail Achatina (Lissachatina) fulica (Bowdich, 1822) (Gastropoda: Achatinidae), vector of Angiostrongylus cantonensis (Nematoda: Angiostrongylidae), in Havana, Cuba". Molluscan Research. 35 (2): 139–142. doi:10.1080/13235818.2014.977837.
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- Ademolu, K. O.; Idowu, A. B.; Mafiana, C. F.; Osinowo, O. A. (2005-03-21). "Performance, proximate and mineral analyses of African giant land snail (Archachatina marginata) fed different nitrogen sources". African Journal of Biotechnology. 3 (8): 412–417. ISSN 1684-5315.
- Nisbet, R. H. (1961). "Some Aspects of the Structure and Function of the Nervous System of Archachatina (Calachatina) marginata (Swainson)". Proceedings of the Royal Society of London B: Biological Sciences. 154 (955): 267–288. doi:10.1098/rspb.1961.0032.
- Voss, M.; Schmidt, H. (2001). "Electrophysiological responses to thermal stimuli in peripheral nerves of the African giant snail, Archachatina marginata S.". Journal of Thermal Biology. 26 (1): 21–27. doi:10.1016/S0306-4565(00)00021-8. PMID 11070341.
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