Achatina fulicagiant african snail

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Geographic Range

Achatina fulica originated in the coastal areas and islands of East Africa, where it presumably got the nickname, “Giant African Snail.” The snail inhabits countries ranging from Mozambique in the south, to Kenya and Somalia in the north. It is not only found in East Africa on the coastal areas and islands, but it has also been introduced to many other countries in Africa, along with many countries worldwide. The snail has been introduced into countries as far apart as the United States to Australia, and countries in-between. Achatina fulica is not a migratory species and has therefore been introduced through other means to the countries outside of East Africa, possibly through agricultural transportation, commerce, trade, vehicle attachment, smuggling, and other accidental and purposeful ways. ("Achatina fulica", 2014a; "Giant African snail", 2013; "Lissachatina fulica", 2014; "Snails (Giant East African Snail)", 2012; Cowie, 2010; Egonmwan, 2007; Stokes, 2006; Vogler, et al., 2013)

Habitat

The giant African land snail has a natural habitat located in Africa, where there is a tropical climate with warm, year round temperatures, and high humidity. The snail has adapted and has been able to thrive in temperate climates as well. This species prefers areas of low to mid-elevation, with temperature preference between nine degrees Celsius and twenty-nine degrees Celsius. Achatina fulica can survive less ideal conditions, such as two degrees Celsius by hibernation and thirty degrees Celsius by aestivation. The snail can be found in agricultural areas, coastal areas, wetlands, disturbed areas, forests, urban areas, and riparian zones. The snails need temperatures above freezing and preferably high humidity in order to thrive the best. They have adapted to dry and cooler areas, however, by being able to hibernate in soft soil during the unfavorable weather conditions. ("Achatina fulica", 2014a; "Snails (Giant East African Snail)", 2012; Cowie, 2010; Stokes, 2006; Vogler, et al., 2013)

Physical Description

The giant African snail can be distinguished from other snails due to their large size; when mature, the snail can reach up to eight inches (30 centimeters) in length with a diameter of four inches (10 centimeters). The snail can reach up to thirty-two grams in weight. The snail has the physical features that are associated with the phylum Mollusca, including a shell. The shell of Achatina fulica is cone-shaped and has a height that is twice that of the width. When the snail is mature and full-grown, the shell will normally consist of seven to nine whorls. The color of the snail differs depending on the environment, as some are primarily brown or dark colored, with dark stripes and streaks that run across the whorls, while others are reddish-brown with pale yellow vertical markings. ("Achatina fulica", 2014a; "Achatina fulica", 2014b; "Giant African Land Snail", 2008; "Giant African snail", 2013; "Pest Alert", 2011; "Snails (Giant East African Snail)", 2012; Cowie, 2010; Stokes, 2006)

  • Average mass
    32 g
    1.13 oz
  • Range length
    30 (high) cm
    11.81 (high) in

Development

The fertilized eggs of A. fulica are laid in a nest, or in the dirt and leaves, so as to protect and disguise the eggs. The eggs then hatch and become immature snails, which grow to adulthood in about six months. Achatina fulica is one of many land snails, which do not have a larvae phase like other Gastropod species. ("Achatina fulica", 2014a; "Achatina fulica", 2014b)

Reproduction

Achatina fulica is hermaphroditic; each individual snail has both male and female reproductive parts. There are no distinguishing parts separating sexes because each snail contains both sex reproductive systems. They do not self-fertilize, so the snails need to mate with another snail of their species. As a Stylommatophiora, Achatina fulica does not mate randomly; the snails mate with respect to age and size of other snails. Immature, small snails that are still growing produce only spermatozoa, while larger, mature adults produce both spermatozoa and ova. There is an age dependent mate choice when it comes to young snails because they need and prefer older adults to mate with. Young giant African snails copulate at all hours of the night, while older adults mate in the middle of the night. The snails choose their mates with respect to size and age, but the reproductive stage-dependent mate is a more attractive mate than the body size-dependent mate choice. Mating occurs when one snail encounters a prospective partner that the individual snail deems acceptable to mate with. When two individual snails mate, there is a possibility that gametes will be transferred to each one by the other simultaneously. However, this is only the case if the snails are around the same size. If there is a size difference, the larger snail will act as the female and the gametes will only be transferred from the smaller snail to the larger snail, mating unilaterally. ("Achatina fulica", 2014a; "Giant African Land Snail", 2008; "Giant African snail", 2013; "Lissachatina fulica", 2014; "Pest Alert", 2011; Cowie, 2010; Egonmwan, 2007; Tomiyama, 1996)

When two A. fulica encounter and deem each other worthy mates, they will mate by one mounting the shell of the other. The mating will begin once the two snails exchange sperm with one another. The sperm is used to fertilize the eggs in the snails, but it can also be stored inside the body for up to two years. The fertilized eggs are laid between eight and twenty days after mating has occurred, and are deposited in nests or among rocks and soils on the ground. The eggs usually hatch at temperatures above fifteen degrees Celsius. The eggs, under the right conditions, will hatch after eleven to fifteen days into small snails. The number of eggs that an individual snail lays often depends on the maturity and age of the snail and is between 100 to 500 eggs. Giant African snails have no specific season of mating, as they are able to produce new clutches every two to three months. ("Achatina fulica", 2014a; "Giant African snail", 2013; Egonmwan, 2007; Tomiyama, 1996)

  • Breeding interval
    The giant African snail breeds every two to three months.
  • Breeding season
    Breeding can take place any time of the year.
  • Range number of offspring
    100 to 500
  • Average number of offspring
    200
  • Range gestation period
    11 to 15 days
  • Average age at sexual or reproductive maturity (female)
    6 months
  • Average age at sexual or reproductive maturity (male)
    6 months

The parents of Achatina fulica do not contribute to the lives of their offspring except for fertilization and laying of the eggs in nests or soil. Once the eggs are hatched, the small individuals are on their own and adopt the territory that their parent provided them. (Cowie, 2010; Egonmwan, 2007)

  • Parental Investment
  • pre-hatching/birth
    • provisioning

Lifespan/Longevity

Achatina fulica can live on average between three and five years, with some individuals reaching as old as ten years. There is not much difference between the lifespans in the wild and in captivity. In their natural habitat, predators are a main cause of mortality of Achatina fulica, however as they have become an invasive species, their new habitats contain close to zero predators. The snails usually die due to natural causes or non-favorable living conditions. Recently, there have been developments in molluscicides that have been impactful on killing this species, in order to better control their population in unwanted areas. ("Achatina fulica", 2014a; "Lissachatina fulica", 2014; Cowie, 2010)

  • Range lifespan
    Status: wild
    10 (high) years
  • Typical lifespan
    Status: wild
    3 to 5 years
  • Typical lifespan
    Status: captivity
    3 to 5 years

Behavior

Achatina fulica is a solitary species. The parents do not have an impact in their offsprings’ lives once the eggs are hatched, so the solitary behavior is intact from the beginning. It is not possible for A. fulica to self-fertilize, so courtship and interaction is a necessary aspect of their lives. Movement is an important aspect of their lives as it is necessary for mating, finding food, and escaping threats. Achatina fulica secretes a slime-like substance that allows for smooth and easy travel during its movement. The substance protects and allows travel across rough and sharp surfaces. Achatina fulica is a nocturnal species and lies dormant during the day. The snails often bury themselves in soil, in order to stay cool and remain hidden from threats. Giant African snails can also survive cold conditions by aestivating; they become slow and sluggish as they wait for warmer and more desired conditions to occur. ("Lissachatina fulica", 2014; "Pest Alert", 2011)

Communication and Perception

Achatina fulica does not need to communicate often, as it is not a social species. The time of communication among the species takes place in the process of mating, as one will mount the back of another individual. Communication takes place as there is a change in the position of the head, along with changes in the movement of the body. The changes in the body and head are communication cues that indicate that the mating process will continue. Achatina fulica does not have hearing as a sense, so it relies on its other senses to perceive the environment. This species also has caudal tentacles; the upper pair of tentacles have eyes at the tips and the lower pair have the sensory organ that allows for smell. This species has a strong sense of smell, which assists in finding food sources. The combination of smell and sight is how this species perceives the environment around them and allows for the detection of food, mates, and potential threats. ("Achatina fulica", 2014a; "Giant African snail", 2013; Cowie, 2010; Egonmwan, 2007)

Food Habits

Giant African snails are herbivores. Achatina fulica feeds primarily on vascular plant matter, having no preference whether it is living or dead matter. This snail species has a strong sense of smell that assists in attracting and leading the individuals to garden crops and other plant resources. These snails have different preferences with their ages; young members of this species feed on decaying matter and unicellular algae. They also prefer soft textured Musa (bananas), Beta vulgaris (beets), and Tagetes patula (marigolds). More mature and developed African snails prefer to feed on living plants and vegetation. The mature snails broaden their spectrum of preferred plants to consume including: Solanum melongena (eggplant), Cucumis sativus (cucumber), Cucurbita pepo (pumpkin), and many others. This species has also been found to feed on other snails, lichens, fungi, and animal matter. The radula, a distinguishing characteristic of Gastropods, is essential in the ability to eat a variety of foods. The radula is a toothed ribbon used to scrape or cut food, and allows for the ability to pick up food and begin the digestive process with ease. ("Achatina fulica", 2014a; "Giant African Land Snail", 2008; "Lissachatina fulica", 2014; "Snails (Giant East African Snail)", 2012; Cowie, 2010)

  • Animal Foods
  • mollusks
  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit
  • flowers
  • lichens
  • algae

Predation

Achatina fulica has a shell from the beginning of its life until the end. The shell is used for protection against the environmental conditions and potential predators. The shell also provides protection for the internal organs against outside forces. The colors of A. fulica tend to be more earthy tones, as to not stand out in its environments and to be more camouflaged from the sight of their predators. Predators of Achatina fulica includes many species of rodents, wild boars, terrestrial crustaceans, and other species of snails. ("Giant African Land Snail", 2008; "Lissachatina fulica", 2014; "Snails (Giant East African Snail)", 2012)

Ecosystem Roles

Achatina fulica has several different ecosystem roles. This species decomposes and consumes dead vegetation. The benefit of this ecosystem role is that the snail assists in recycling nutrients and the building blocks essential to life. Giant African snails are also part of the food chain, as they are a source of food to many predators. This species is also a host to parasitic organisms, such as Angiostrongylus cantonensis, the rat lungworm. The parasitic organisms live and thrive on this host and can be transported to other hosts, such as humans, through the consumption of the snails. ("Achatina fulica", 2014a; "Achatina fulica", 2014b; Carvalho, et al., 2003; Cowie, 2010; Stokes, 2006)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Snails are often seen as a delicacy for humans and A. fulica is no exception. Humans around the world consume giant African snails as a source of protein when prepared correctly. This species is also a cheap alternative in some regions as a source of fish feed in fish farming, as they breed quickly and in large amounts. Achatina fulica can also be beneficial in making fertilizer, chicken feed, and biological compounds in clinical and experimental laboratories. ("Achatina fulica", 2014a; "Lissachatina fulica", 2014; Stokes, 2006)

Economic Importance for Humans: Negative

Giant African snails are an invasive species across that world. It has become illegal to have possession of these snails in countries where it has been introduced. Achatina fulica has a large and broad diet preference; the dietary habits of this species cause a high loss in crops for farmers. They are considered an agricultural pest, costing farmers not only their crops but also economic costs. This species is also a carrier of many parasitic organisms, including organisms that harm people and plants. Serious illness and diseases can erupt in humans if they consume giant African snails. Achatina fulica also destroys and pollutes its surroundings, including soil. When an individual of this species dies, the calcium carbonate found in the shells neutralizes the soil; the neutralization of the soil and the altering of its properties affect the types of plants that can grow in the soil. Achatina fulica can cost cities, states, or countries millions of dollars in not only agricultural costs, but also in attempts to control this invasive species. ("Achatina fulica", 2014a; "Achatina fulica", 2014b; "Giant African Land Snail", 2008; "Lissachatina fulica", 2014; "Species Profiles: Giant African Snail", 2014; Carvalho, et al., 2003; Cowie, 2010; Stokes, 2006)

Conservation Status

Achatina fulica is not currently vulnerable, threatened, nor endangered.

Contributors

Taylor Hoffman (author), Grand View University, Nicole Pirie (author), Grand View University, Felicitas Avendano (editor), Grand View University, Dan Chibnall (editor), Grand View University, Angela Miner (editor), Animal Diversity Web Staff.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

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Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

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Neotropical

living in the southern part of the New World. In other words, Central and South America.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

biodegradation

helps break down and decompose dead plants and/or animals

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chemical

uses smells or other chemicals to communicate

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

induced ovulation

ovulation is stimulated by the act of copulation (does not occur spontaneously)

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

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oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

protandrous

condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

sperm-storing

mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

References

2014. "Achatina fulica" (On-line). Encyclopedia of Life. Accessed March 09, 2014 at http://eol.org/pages/452699/details.

2014. "Achatina fulica" (On-line). Institute for the Study of Invasive Species. Accessed March 07, 2014 at http://www.tsusinvasives.org/database/giant-african-snail.html.

2008. "Giant African Land Snail" (On-line). Massachusetts Introduced Pests Outreach Project. Accessed February 28, 2014 at http://massnrc.org/pests/pestFAQsheets/giantafricanlandsnail.html.

2013. "Giant African snail" (On-line). ARKive. Accessed February 28, 2014 at http://www.arkive.org/giant-african-snail/achatina-fulica/.

2014. "Lissachatina fulica" (On-line). Invasive Species Compendium. Accessed March 07, 2014 at http://www.cabi.org/isc/?compid=5&dsid=2640&loadmodule=datasheet&page=481&site=144.

2011. "Pest Alert" (On-line pdf). United States Department of Agriculture. Accessed March 07, 2014 at http://www.aphis.usda.gov/publications/plant_health/content/printable_version/pa_phgas.pdf.

2012. "Snails (Giant East African Snail)" (On-line). Infonet-Biovision. Accessed March 08, 2014 at http://www.infonet-biovision.org/default/ct/110/pests.

2014. "Species Profiles: Giant African Snail" (On-line). United States Department of Agriculture. Accessed February 26, 2014 at http://www.invasivespeciesinfo.gov/animals/africansnail.shtml.

Carvalho, O., H. Teles, E. Mota, C. Lafeta, G. Mendonca, H. Lenzi. 2003. Potentiality of Achatina fulica Bowdich, 1822 (Mollusca: Gastropoda) as intermediate host of the Angiostrongylus costaricensis Morera & Céspedes 1971. Revista da Sociedade Brasileira de Medicina Tropical, 36/6: 743-745. Accessed March 06, 2014 at http://www.scielo.br/pdf/rsbmt/v36n6/a17v36n6.pdf.

Cowie, R. 2010. "Achatina fulica (mollusc)" (On-line). Global Invasive Species Database. Accessed March 06, 2014 at http://www.issg.org/database/species/ecology.asp?si=64&fr=1&sts=sss&lang=N..

Egonmwan, R. 2007. "Recent Advances in the Biology of Giant African Land Snails" (On-line pdf). Federal University of Agriculture, Abeokuta. Accessed March 05, 2014 at http://unaab.edu.ng/netgals/downloads/Egonmwan.pdf.

Stokes, H. 2006. "Introduced Species Summary Project" (On-line). Columbia University. Accessed March 04, 2014 at http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Achatina_fulica.htm#Introduction_Facts.

Tomiyama, K. 1996. MATE-CHOICE CRITERIA IN A PROTANDROUS SIMULTANEOUSLY HERMAPHRODITIC LAND SNAIL ACHATINA FULICA (FÉRUSSAC) (STYLOMMATOPHORA: ACHATINIDAE). Journal of Molluscan Studies, 62: 101-111. Accessed March 07, 2014 at http://mollus.oxfordjournals.org/content/62/1/101.full.pdf+html.

Vogler, R., A. Beltramino, M. Sede, D. Gregoric, V. Nunez, A. Rumi. 2013. The giant African snail, Achatina fulica (Gastropoda: Achatinidae): Using bioclimaticmodels to identify South American areas susceptible to invasion. American Malacological Bulletin, 31/1: 39-50. Accessed March 04, 2014 at http://www.academia.edu/2602901/The_Giant_African_Snail_Achatina_fulica_Gastropoda_Achatinidae_Using_Bioclimatic_Models_to_Identify_South_American_Areas_Susceptible_to_Invasion.