Lissachatina fulica

Lissachatina fulica is a species of large land snail that belongs in the subfamily Achatininae of the family Achatinidae. It is also known as the Giant African land snail. It shares the common name "giant African snail" with other species of snails such as Achatina achatina and Archachatina marginata. This snail species has been considered a significant cause of pest issues around the world. Internationally, it is the most frequently occurring invasive species of snail.

Outside of its native range, this snail thrives in many types of habitat in areas with mild climates. It feeds voraciously and is a vector for plant pathogens, causing severe damage to agricultural crops and native plants. It competes with native snail taxa, is a nuisance pest of urban areas, and spreads human disease.

Subspecies
Subspecies within this species:
 * Lissachatina fulica castanea (Lamarck, 1822)
 * Lissachatina fulica coloba (Pilsbry, 1904)
 * Lissachatina fulica hamillei (Petit, 1859)

Distribution
The species is native to East Africa, but it has been widely introduced to other parts of the world through the pet trade, as a food resource, and by accidental introduction.

Within Africa, the snail can be found along the eastern coast of South Africa, extending northward into Somalia. However, some of its distribution into northern African may be due to human introduction, starting in northern Mozambique, Tanzania, Kenya, and extending through Somalia into Ethiopia. The snail has been reported in Morocco, Ghana, and the Ivory Coast as early as the 1980s.

In 1961, Albert R. Mead, published the seminal work entitled "The Giant African Snail: A Problem in Economic Malacology". This book compiled known information on the snail, as well as a detailed overview on its global distribution.

Prior to 1800, the snail was found in Madagascar, spreading westward to Mauritius, reaching Réunion in 1821, then to Seychelles in 1840. In 1847, they were introduced to India and in 1900 in Sri Lanka. In 1911, the snail was present in northern Malaysia, possibly from India or Myanmar. In 1922, the snail was identified in Singapore although it may have been present as early as 1917. In 1925, the snail was shipped to Java, from which it spread across Indonesia. In 1928, the snail was observed in Sarawak.

This species has been found in China since 1931 and its initial point of distribution in China was Xiamen. The snail has also been established on Pratas Island, of Taiwan. The species was established in Hawaii, United States, by 1936. The snail was present in Papua New Guinea by 1946, spreading from New Ireland and New Britain to the mainland by 1976–77. By 1967 the snail was present in Tahiti, spreading through New Caledonia and Vanuatu by 1972 into French Polynesia by 1978, including America Samoa.

In 1984, L. fulica was found established in the French West Indies, spreading across Guadeloupe and by 1988 arriving in Martinique.

By 1990, the snail was reported in Samoa and the Federated States of Micronesia in 1998.

In Brazil, the first introduction of L. fulica came in 1988 in Paraná. By 2007, it was recorded in 23 of the 26 Brazilian states. In 2006–08, the snail was recorded in Ecuador, in Pichincha, and may have been present at least 10 years prior in 'snail farms'. The presence of the snail in Colombia was reported by 2008-09. Although the time of the initial introduction is unknown, it has been registered in all regions of the country by 2012. Live specimens were found in Piura, Peru, around 2008 as well. The snail may be present in Venezuela and was reported in Puerto Iguazú, Argentina in 2010.

The species has been observed in Bhutan (Gyelposhing, Mongar), where it is an invasive species since 2006 and their number increased drastically since 2008.

In the contiguous United States, the snail has been reported in the state of Florida in 2011, and later in 2021-22; however, the snail has not established.

Description
The adult snail is around 7 cm in diameter and 20 cm or more in length, making it one of the largest of all extant land snails.

The shell has a conical shape, being about twice as long as it is broad. Either clockwise (dextral) or counter-clockwise (sinistral) directions can be observed in the coiling of the shell, although the 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.

Habitat
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.

Feeding


The giant African snail is a macrophytophagous herbivore; it eats a wide range of plant material, fruit, vegetables, lichens, fungi, paper, and cardboard. It sometimes eats sand, very small stones, bones from carcasses, and even concrete as calcium sources for its shell. In rare instances, the snails consume each other, snail eggs, and other deceased small animals such as mice and birds.

In captivity, this species can be fed on a wide range of fruit and vegetables, plain unseasoned mince, or boiled egg. They should always be provided with a source of calcium carbonate such as cuttlefish bone, vital for healthy shell growth. They require about 20% of crude protein in their diet for optimal growth.

Lifecycle
This snail is a protandric hermaphrodite; each individual has both testes and ovaries and is capable of producing both sperm and ova. The testes typically mature first around 5–8 months, followed by the ovaries. Self-fertilization has been observed and therefore snails do not require a partner to reproduce, however it is relatively rare and the resulting egg clutch is small with low viability. Typically, mating involves a simultaneous transfer of gametes to each other (bilateral sperm transfer, as compared to unilateral sperm transfer), however only the older snail with mature ovaries will produce eggs. Younger, smaller snails are more likely to initiate mating with a mate preference for larger, older snails; although larger, older snails may also mate with each other.

Snails mate at night and their mating begins with courtship rituals that can last up to half an hour, including petting their heads and front parts against each other. One snail initiates the courtship, and if all goes well they begin copulation. However, copulation does not always occur because snails show mate choice behavior, and observations have shown up to 90% of attempted courtships were rejected and did not end in copulation. Copulation can last anywhere from 1–24 hours, but tends to last 6–8 hours. Transferred sperm can be stored within the body up to two years.

The snails are oviparous and lay shelled eggs. The number of eggs per clutch and clutches per year varies by environment and age of the parent, but averages around 200 eggs per clutch and 5–6 clutches per year. The eggs hatch after 8–21 days and the snails emerge as juveniles. They reach adult size in about six months, after which growth slows, but does not cease until death. Life expectancy is 3–5 years in the wild and 5–6 years in captivity, but the snails can live for up to 10 years.

Snails are primarily active at night and spend their days in dark, damp places such as buried in soil or under leaf litter. They are capable of aestivating up to three years in times of extreme drought, sealing itself into its shell by secretion of a calcareous compound that dries on contact with the air.

Parasites
Several different species and types of parasites have been known to infect Lissachatina fulica.


 * Aelurostrongylus abstrusus, also known as "feline lungworm", is a nematode that infects cats.
 * Angiostrongylus cantonensis, also known as "rat lungworm", is a nematode that causes eosinophilic meningoencephalitis. Infected snails have been found in South American countries including Peru, Ecuador, Venezuela, and Brazil. 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, thus causing a life-threatening infection.
 * Angiostrongylus costaricensis is a nematode that causes abdominal angiostrongyliasis.
 * Fasciola gigantica is a flatworm that has been detected in the faeces and intestines of the snail.
 * Hymenolepis is a tapeworm that has been detected in the faeces of the snail.
 * Schistosoma mansoni is a parasitic flatworm that causes intestinal schistosomiasis. Sporocysts of S. mansoni have been detected in snail faeces
 * Strongyloides species, including Strongyloides stercoralis, are roundworms that have been detected in faeces and in mucous secretion of the snail.
 * Trichuris is a roundworm that has been detected in the faeces of the snail.

As an invasive species
In many places, this snail is a pest of agriculture and households, with the ability to transmit both human and plant pathogens. Suggested preventive measures include strict quarantine to prevent introduction and further spread. This snail 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.

This snail was twice established in southeastern Florida and was successfully eradicated both times. They were brought to the U.S. through imports, intended for educational uses and to be pets. Some were also introduced because they were accidentally shipped with other cargo. An eradication effort in Florida began in 2011 when they were first sighted, and the last sighting was in 2017. In October 2021 the Florida Department of Agriculture declared the eradication a success after no further sightings in those four years. In June 2022 the snail was again found in Florida.

They are also known to damage buildings by eating stucco and similar materials for the calcium.

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, thus causing 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 World War II and they escaped. A carnivorous species (Florida rosy wolfsnail, Euglandina rosea) was later introduced by the United States government, in an attempt to control A. fulica, but the rosy wolf snail instead heavily preyed upon the native Partula snails, causing the extinction of most Partula species within a decade.

The snail has been eradicated from California, U.S., Queensland, Australia, Fiji, Western Samoa, Vanuatu, and Wake Island, but these were relatively small populations.

The National Agricultural Health Service has established an ongoing project to detect, study, and prevent the expansion of this pest.

In early April 2021, USCBP intercepted 22 being smuggled from Ghana into the US, along with various other prohibited quarantine items.

Human use


These snails 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 West African giant snail (Archachatina marginata) normally offered in Nigeria. The two species are similar enough in appearance to satisfy religious authorities. They are also edible if cooked properly. In Taiwan, this species is used in the dish of 炒螺肉 (fried snail meat), which is a delicacy among the traditional drinking snacks. L. fulica also constitutes the predominant land snail found in Chinese markets, and larger species have potential as small, efficient livestock.

The snails have also become increasingly popular as pets  in some countries, where various companies have sold the animal both as a pet and an education aide. In light of social media posts where pet owners share images in close contact with the snails, a research from the University of Lausanne alerted with the risks of infections transmitted to humans.

The heparinoid, acharan sulfate, is isolated from this species.