Achatina Achatina (giant snail, tiger snail), a widely distributed species in West Africa (particularly in Benin, Côte d’Ivoire, Ghana, Liberia, Nigeria, Sierra Leone and Togo), can be considered a good candidate for snail farming in most areas of West Africa, although it requires higher humidity than the other two species and needs a longer growing time to reach sexual maturity.
Description of Achatina Achatina
Achatina achatina snails are reputedly the largest land snails in the world. Although usually much smaller, they can grow up to 30 cm in body length and 25 cm in shell height.
Average adult shell length is 18cm, with an average diameter of 9 cm. The conically shaped, fairly pointed shell is brownish with a characteristic stripe pattern (hence the name tiger snail).
Distribution of Achatina Achatina
Achatina achatina originates from the West African rainforest belt, from Guinea through Nigeria. Because A. achatina is the most prized species for consumption in Ghana it is becoming increasingly rare in the wild.
Several ecotypes (locally adapted populations of A. achatina) can be found, with differences in growth rates, size, aestivation (dormancy) patterns, color and even flavor. The differences in size may be explained partly by differences in the length of the aestivation period; the shorter the aestivation period, the longer the feeding period and the larger, therefore, the ecotype.
A study of the three ecotypes in Ghana, known as donyina, apedwa and goaso, showed significant differences between them. The apedwa snails had the shortest aestivation periods, the donyina snails the longest.
The apedwa snails were the largest of the three ecotypes; some were twice the size of Donyina snails. In Ghana, this ecotype would be recommended as the best candidate for snail farming.
Growing conditions of Achatina Achatina
The species prefers warm conditions, 25-30 °C and a relative humidity of 80-95%. A. achatina is said not to be the easiest species to farm because of the very steady conditions it is used to in the wild: a practically constant 12/12 photo-period, only extending to 13/11 for about 3 months, and a temperature difference between night and day of only 2-4 °C. Even in the most humid areas of West Africa the snail, in its natural habitat, buries itself for aestivation during the drier months.
Life history of Achatina Achatina
Reproduction: Achatina achatina reproduces by self-fertilization. Unlike in many other species, reproduction is not preceded by coupling, although it is not unusual to find two snails in close proximity.
Studies (Hodasi, 1979) indicate that the species breeds in the main rainy season (April-July in Ghana). Laying. Laying usually takes place in the late evening and night. Eggs are laid in clutches of 30-300 eggs. They are broadly oval, dirty yellowish, 8-9 mm long and 6-7 mm wide. Eggs are deposited in dug-out holes about 4 cm deep. When small clutches of eggs are laid, a second laying is indicated, and sometimes a third.
Hatching: Usually, the eggs hatch 2-3 weeks after laying, with a range of 10-31 days, depending on temperature. A. achatina has a high hatching rate of 90+%; even 100% hatchability is not uncommon.
The baby snail has a thin shell membrane which calcifies progressively. Although this period is characterized by rapid growth, the snails are able to survive the first few days (5-10 days) after hatching without food.
Juveniles: The juvenile phase covers the period from 1 or 2 months to the stage of sexual maturity (14-20 months). During this period, the snail accepts a much wider range of food. At the end of the period, the shell is well formed and the snail weighs between 100 and 450 g. Differences in growth rates of the various ecotypes are very evident during this period.
Adults: The adult phase starts when the snail reaches sexual maturity. Not all adult snails lay eggs each season. An average life expectancy is 5 to 6 years, although there are reports of snails surviving up to 9 or 10 years.
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