Achatina Achatina (giantsnail, tiger snail), a widely distributed species in West Africa (particularlyin Benin, Côte d’Ivoire, Ghana, Liberia, Nigeria, Sierra Leone and Togo), canbe 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 alonger growing time to reach sexual maturity.
Achatina achatina snails arereputedly 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. Averageadult shell length is 18cm, with an average diameter of 9 cm. The conicallyshaped, fairly pointed shell is brownish with a characteristic stripe pattern(hence the name tiger snail).
Achatina achatina originatesfrom the West African rainforest belt, from Guinea through Nigeria. Because A.achatina is the most prized species for consumption in Ghana it is becomingincreasingly rare in the wild.
Several ecotypes (locallyadapted populations of A. achatina) can be found, with differences in growthrates, size, aestivation (dormancy) patterns, color and even flavor. Thedifferences in size may be explained partly by differences in the length of theaestivation period; the shorter the aestivation period, the longer the feedingperiod and the larger, therefore, the ecotype.
A study of the three ecotypesin Ghana, known as donyina, apedwa and goaso, showed significant differencesbetween them. The apedwa snails had the shortest aestivation periods, thedonyina snails the longest. The apedwa snails were the largest of the threeecotypes; some were twice the size of Donyina snails. In Ghana, this ecotypewould be recommended as the best candidate for snail farming.
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.
Reproduction:Achatina achatina reproduces by self-fertilization. Unlike in many otherspecies, reproduction is not preceded by coupling, although it is not unusualto 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+%; even100% hatchability is not uncommon.
The baby snail has a thinshell membrane which calcifies progressively. Although this period ischaracterized by rapid growth, the snails are able to survive the first fewdays (5-10 days) after hatching without food.
Juveniles:Thejuvenile phase covers the period from 1 or 2 months to the stage of sexualmaturity (14-20 months). During this period, the snail accepts a much widerrange of food. At the end of the period, the shell is well formed and the snailweighs between 100 and 450 g. Differences in growth rates of the variousecotypes are very evident during this period.
Adults:Theadult phase starts when the snail reaches sexual maturity. Not all adult snails lay eggs each season. Anaverage life expectancy is 5 to 6 years, although there are reports of snailssurviving up to 9 or 10 years.