Giant African snail (Achatina fulica)

Description

Giant African snail fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Giant African snail description

Classed as one of the world’s most invasive species, the giant African snail (Achatina fulica) has been introduced around the world from its native home in eastern Africa ⁽²⁾. In general, the shell of the giant African snail is a reddish-brown colour, with pale yellow vertical markings ^{(2) (3)}, although colouration can vary depending on the surrounding environmental conditions ⁽²⁾. When fully grown, the shell of the giant African snail has seven to nine whorls, and is most often narrow and conical in shape; however, some individuals appear much broader and shorter, while others are much taller and more slender ^{(2) (3) (4)}.  

Size

Length: up to 20 cm ⁽²⁾

Weight

up to 32 g ⁽²⁾

Giant African snail biology

The giant African snail is a hermaphrodite, meaning that each individual has both male and female reproductive organs ^{(2) (3) (4) (5)}. Courtship begins as soon as it encounters a prospective partner, with one individual approaching the other from behind, and mounting the shell. If the snail that has been mounted accepts the potential mate, it will bend its head backwards and begin to rock its body, and the pair will then proceed to mating ⁽⁵⁾. In order to reproduce, the two individuals must engage in a reproductive behaviour known as ‘reciprocal copulation’, where sperm from one snail is used to fertilise the eggs in the other, and vice versa ^{(3) (4) (5)}. The eggs are usually laid between 8 and 20 days after copulation has taken place, although the giant African snail is capable of storing sperm for much longer, and the eggs are generally deposited in a nest that has been excavated in the soil, or among leaves and stones ^{(4) (5)}. The number of eggs laid in each clutch depends on the age of the snail, although it is usually between 100 and 500 eggs. The young snails hatch after around 11 to 15 days, depending on the temperature and the local conditions ^{(4) (7)}.

Mainly active at night, the giant African snail feeds on living or dead plant matter from as many as 500 different plant species, including many economically valuable crops such as cabbage, cauliflower, cacao and banana, as well as many others ^{(2) (3) (4)}.

Giant African snail range

The giant African snail naturally occurs throughout the coastal area and islands of East Africa, ranging from Mozambique in the south, to Kenya and Somalia in the north. It has also been introduced to many other areas of Africa, including Morocco, the Ivory Coast and Ghana ^{(2) (5)}. Worldwide, the giant African snail has been introduced to the Indian Ocean islands, throughout parts of Asia (particularly in the South East and Pacific regions), and is also known to occur in the Caribbean and Australia ^{(2) (5) (6)}.

Giant African snail habitat

Within its natural East African range, the giant African snail is often abundant in forest margins ⁽⁵⁾. Elsewhere, this species appears to be well adapted to modified habitats, including plantations, gardens and disturbed sites at low to mid elevations, as well as invading primary and secondary forests ^{(2) (5)}. The giant African snail also occurs in agricultural areas, along the edges of streams and rivers, in scrublands, and in urban areas ⁽⁴⁾.

Giant African snail status

The giant African snail has yet to be classified by the IUCN.

Giant African snail threats

There are no known threats to the giant African snail.

In fact, the giant African snail is widely considered one of the worlds’ most invasive species, and has been listed among the “100 World's Worst Invasive Alien Species” by the Global Invasive Species Database ^{(2) (4)}. It is illegal to import this species into many countries ⁽²⁾. Outside of its natural range, this snail is considered a major agricultural pest, and may also threaten native snails and ecosystems in areas where it has been introduced. It is also a carrier of several parasites, some of which are harmful to humans if ingested, while others increase the spread of plant diseases (particularly the black pod disease in cacao plants) ^{(3) (4)}.

Giant African snail conservation

There are currently no conservation measures specifically targeted at this species. In some areas of the world where the giant African snail is considered to be a pest species, eradication programmes have been established to prevent further damage to crops and to native plants, snails and ecosystems.

Find out more

For more information on the giant African snail and its role as an invasive species:

• The Asia-Pacific Invasive Species Network:
  http://www.fao.org/world/regional/rap/invasives/invasives/fact_sheet1.pdf

Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

Glossary

Fertilise

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Parasites

Organisms that derive food from, and live in or on, another living organism at the host’s expense.

Primary forest

Forest that has remained undisturbed for a long time and has reached a mature condition.

Secondary forest

Forest that has re-grown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.

Whorls

In animals, the spirals or convolutions in the shell of a snail.

References

1. ITIS (August, 2010)
   http://www.itis.gov/
2. Global Invasive Species Database (August, 2010)
   http://www.issg.org/database/species/ecology.asp?si=64
3. United States Department of Agriculture, Animal and Plant Health Inspection Service: Achatina fulica factsheet (August, 2010)
   http://www.aphis.usda.gov/plant_health/plant_pest_info/gas/downloads/achatinafulica.pdf
4. Asia-Pacific Invasive Species Network: Pest factsheet (August, 2010)
   http://www.fao.org/world/regional/rap/invasives/invasives/fact_sheet1.pdf
5. Raut, S.K. and Barker, G.M. (2002) Achatina fulica Bowdich and other Achatinidae as pests in tropical agriculture. In: Barker, G.M. (Ed.) Molluscs as Crop Pests. CABI Publishing, Oxon, UK.
6. North American Plant Protection Organisation: Pest Alert (August, 2010)
   http://www.pestalert.org/Detail.CFM?recordID=10
7. Secretariat of the Pacific Community: Pest Alert (August, 2010)
   http://www.spc.int/pps/PestAlerts/AgAlertNo15.pdf