Distributions – “East Africa, Madagascar, Reunion, Mauritius, India, Ceylon, Malaya, Siam, S. China, S. Japan, Sumatra, Java, Borneo, Celebes, seeral Lesser Sunda Is., New Guinea, Philippines, Guam, Saipan, Tinian Is., New Britain, new Ireland, Hawaiian Is., Palau Is., Okinawa, S. California” (Benthem-Jutting, 1952)
Global Range: Introduced into Hawaii (Cowie, 1997; 1998) and Samoa (Cowie and Cook, 1999).
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Benthem-Jutting (1952) descriptions on Achatina fulica – “Shells large, solid, pyramidal with produced spire and rounded base. Ground colour light yellow or fawn, ornated with irregular brown or mauve vertical bans, streaks or blothes under a greenish-yellow epidermis. With soft lustre, little or not transparent. Coarsely striated in vertical direction. Towards the suture and towards the aperture the striae become almost rib-like. In many specimens there is a finer spiral sculpture also, especially on the whorls of the spire, rendering this part of the shell a decussated appearance. The whole is covered by a yellowish or brownish periostracum which peels off easily. Whorls 7 to 9, rapidly increasing in size, moderately convex. The last one large and rather inflated. Top whorls smooth. Umbilicus close, even in young individuals. Suture irregularly crenulated, occasionally lightly margined. Aperture somewhat oblique, broad-oval, pointed above and below. Height of aperture shorter than the spire. Peristome not continuous, the two ends connected by a thin, white callus against the parietal wall. Outer margin sharp, not thickened or reflected. Interior white or bluish-white. In the interior of young shells the flames of the outside colour pattern are shining through. Columellar margin thickened, slightly tortuous longitudinally and truncated at the lower end.”
Achatina fulica – “Dimensions: height 100 to 130 mm, in exceptional cases till 170 mm, width 45 to 60 mm, height of aperture 50 to 55 mm.” (Benthem-Jutting, 1952)
SubSpecies Varieties Races
“Achatina fulica has a predilection for plantations, vegetable gardens, refuse heaps etc. where it feeds on fresh and decaying plants, not even respecting such well-armed plants as Opuntia and Euphorbia. It is sometimes found eating latex in rubber plantations. Generally they live on the ground, but occasionally they climb tree trunks. In the dry season they hide away in the soil, retract in their shells and close it with a thin epiphragm. Achatina fulica inhabits the lower altitudes: lowland plains and hilly country up to about 1000 m altitude, mostly in or near human settlements. It has not been found in truly “wild” conditions, and not in tropical rain forest or in the higher mountains.” (Benthem-Jutting, 1952)
“During the Japanese occupation of the Malay Archipelago (1942-1945) Achatina fulica was purposely introduced for food in several internment camps. The once so highly depised snail now became an appreciated source of animal protein for the straving prisoners. In this way it was transported from island to island and has rapidly conquered new areas acclimatizing perfectly in its new surroundings.” (Benthem-Jutting, 1952)
Predators of Achatina fulica – “Malaysian wood rat, Rattus tiomanicus (Miller); Pacific rat, Rattus exulans (Peale); Rice field rat, Rattus argentiventer (Robinson & Kloss); Pig, Sus scrofa (Linnaeus).” (Limm, 1966)
Diseases and Parasites
The snails play a pivotal role in eosinophilic meningoencephalitis. This condition is caused by worm parasites. The parasites enter an organism as an intermediate host or through ingestion of contaminated water. The central nervous system will then be affected and death could result if left untreated (Graeff-Teixeira et al, 2009). A study completed in northeast Brazil concluded that the giant African snails act as an intermediate host for this condition (Thiengo, 2010). This snail enters the respiratory system and if eaten uncooked, death could result from eosinophilic meningoencephalitis (Civeyrel & Simberloff, 1996).
Life History and Behavior
Molecular Biology and Genetics
Statistics of barcoding coverage: Achatina fulica
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Relevance to Humans and Ecosystems
In West Africa, Giant African Snails are one of the main sources of protein (Hardouin, 1995). Additionally, they may also suppress tumor growth in cancer. Angiogenesis is the formation of new capillaries that contributes to the growth and metastasis of cancer tumors. In a study of mice, it was found that Archaran sulfate, a substance found in the giant African snails could be used to inhibit angiogenesis and also act as an antitumor agent (Lee et al, 2003).
Because the snails are herbivores, they can consume a large amount of crops and plants. This leaves farmers with major crop and income losses every year; eliminating the snail pests is also not a viable option as it is extremely costly (Stokes, 2006).
Achatina fulica is a species of land snail in the family Achatinidae known commonly as the giant African snail or giant African land snail. It thrives in many types of habitat in areas with mild climates, it feeds voraciously and vectors plant pathogens, causing severe damage to agricultural crops and native plants, it competes with native snail taxa, it is a nuisance pest of urban areas, and it spreads human disease. It is listed as one of the top 100 invasive species in the world.
- Achatina fulica hamillei Petit, 1859
- Achatina fulica rodatzi Dunker, 1852
- Achatina fulica sinistrosa Grateloup, 1840
- Achatina fulica umbilicata Nevill, 1879
This species has been found in China since 1931 (map of distribution in 2007), and its initial point of distribution in China was Xiamen. The snail has also been established in the Pratas Islands, of Taiwan, throughout India, the Pacific, Indian Ocean islands, and the West Indies. In the United States, it has become established in Hawaii and eradication is underway in Florida.
The species has recently been observed in Bhutan (Gyelposhing, Mongar), where it is an invasive species. It has begun to attack agricultural fields and flower gardens. It is believed there that dogs which have consumed the snail died as a result.
The adult snail is around 7 centimetres (2.8 in) in height and 20 centimetres (7.9 in) or more in length.
The shell has a conical shape, being about twice as high as it is broad. Either clockwise (dextral) or counter-clockwise (sinistral) directions can be observed in the coiling of the shell, although the right-handed (dextral) cone is the more common. Shell colouration is highly variable, and dependent on diet. Typically, brown is the predominant colour and the shell is banded.
The giant African snail is native to East Africa, and can be traced back to Kenya and Tanzania. It is a highly invasive species, and colonies can be formed from a single gravid individual. In many places, release into the wild is illegal. Nonetheless, the species has established itself in some temperate climates and its habitat now includes most regions of the humid tropics, including many Pacific islands, southern and eastern Asia, and the Caribbean. The giant snail can now be found in agricultural areas, coastland, natural forest, planted forests, riparian zones, scrub and shrublands, urban areas, and wetlands.
The giant African snail is a macrophytophagous herbivore; it eats a wide range of plant material, fruit, and vegetables. It will sometimes eat sand, very small stones, bones from carcasses and even concrete as calcium sources for its shell. In rare instances the snails will consume each other.
In captivity, this species can be fed on grain products such as bread, digestive biscuits, and chicken feed. It can be supplemented with calcium for shell development. It requires about 18.28% of crude protein in its diet for optimal growth.
This species is a simultaneous hermaphrodite; each individual has both testes and ovaries and is capable of producing both sperm and ova. Instances of self-fertilization are rare, occurring only in small populations. Although both snails in a mating pair can simultaneously transfer gametes to each other (bilateral mating), this is dependent on the size difference between the partners. Snails of similar size will reproduce in this way. Two snails of differing sizes will mate unilaterally (one way), with the larger individual acting as a female. This is due to the comparative resource investment associated with the different genders.
Like other land snails, these have intriguing mating behaviour, including petting their heads and front parts against each other. Courtship can last up to half an hour, and the actual transfer of gametes can last for two hours. Transferred sperm can be stored within the body for up to two years. The number of eggs per clutch averages around 200. A snail may lay five to six clutches per year with a hatching viability of about 90%.
Adult size is reached in about six months, after which growth slows, but does not ever cease. Life expectancy is commonly five or six years in captivity, but the snails may live for up to ten years. They are active at night and spend the day buried underground.
The giant African snail is capable of aestivating for up to three years in times of extreme drought, sealing itself into its shell by secretion of a calcerous compound that dries on contact with the air. This is impermeable; the snail will not lose any water during this period.
Parasites of Achatina fulica include:
- Aelurostrongylus abstrusus
- Angiostrongylus cantonensis - causes eosinophilic meningoencephalitis
- Angiostrongylus costaricensis - causes abdominal angiostrongyliasis
- Schistosoma mansoni - causes schistosomiasis, detected in faeces
- Trichuris spp. - detected in faeces
- Hymenolepis spp. - detected in faeces
- Strongyloides spp. - detected in faeces and in mucous secretion
As an invasive species
In many places the snail is a pest of agriculture and households with the ability to transmit human and plant pathogens. Suggested preventative measures include strict quarantine to prevent introduction and further spread. It has been given top national quarantine significance in the United States. In the past, quarantine officials have been able to successfully intercept and eradicate incipient invasions on the mainland USA.
In the wild, this species often harbors the parasitic nematode Angiostrongylus cantonensis, which can cause a very serious meningitis in humans. Human cases of this meningitis usually result from a person having eaten the raw or undercooked snail, but even handling live wild snails of this species can infect a person with the nematode and cause a life-threatening infection.
In some regions, an effort has been made to promote use of the giant African snail as a food resource to reduce its populations. However, promoting a pest in this way is a controversial measure, because it may encourage the further deliberate spread of the snails.
One particularly catastrophic attempt to biologically control this species occurred on South Pacific Islands. Colonies of A. fulica were introduced as a food reserve for the American military during the second world war and they escaped. A carnivorous species (Florida rosy wolfsnail, Euglandina rosea) was later introduced by American government, but it instead heavily harvested the native Partula, causing the loss of most Partula species within a decade.
Achatina fulica are used by some practitioners of Candomblé for religious purposes in Brazil as an offering to the deity Oxalá. The snails substitute for a closely related species, the African giant snail (Archachatina marginata) normally offered in Nigeria. The two species share a common name (Ìgbín, also known as ibi or boi-de-oxalá in Brazil), and are similar enough in appearance to satisfy religious authorities. They are also edible if cooked properly.
This article incorporates CC-BY-2.0 text from the reference.
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