Strictly speaking this post is in the wrong section. But I am without another option as I cannot find molluscs listed anywhere as a thread... So, if need be, someone good at brooming can sweep it elsewhere! Giant African Land Snails (Achatina fulica)
are fascinating animals. They love wet weather and when a rainy day comes around chances are good that you will see a GALS somewhere in the Lowveld busy relocating. I "shot" this one near Skukuza.
They secrete mucus from the foot to aid locomotion by reducing friction and to help reduce the risk of mechanical injury from sharp objects. They can crawl over a sharp edge like a straight razor and not be injured! At best they can cover a smooth, flat area at around 150 millimetres per minute! That is a gallop in terms of snail pace!
Giant African Land snails bear two pairs of tentacles on their heads. The eyes are carried on the upper set of tentacles or 'eye stalks' (located at the tip) which they can move back and forth and up and down to get a better "view". The eyes are incapable of letting the snail see in colour and most probably produce rather blurred vision.
The lower set of tentacles act as olfactory organs (better to smell with, my dear... and actually taste with as well!) Both sets of tentacles are retractable in land snails. Muscles are used to withdraw them, but blood pressure extends them.
Other interesting facts about Giant African Land snails are:
• they grow to 70 mm by the end of their first year, by which time they can reproduce.
• they are hermaphrodites, having reproductive organs normally associated with both male and female sexes, a normal condition for snails, enabling a form of sexual reproduction in which both partners can act as the "female" or "male".
• Each snail can lay up to 1000 eggs per year with clutches ranging from 100 – 400 eggs
• Growth is slow after the first year with snails living on average 5-6 years to a maximum of 9 years.
• GALS are farmed commercially as popular food items (escargots) and 10s of tonnes of it is consumed in various parts of the world annually.
• As far as protein is concerned, snail meat compares well with traditional sources of protein like chicken meat, pork or beef. The giant escargot substitute is said to be slightly inferior to the European snails as it is ‘rubbery’ and often tastes of swamp. When highly flavoured with garlic, chopped and stuffed into the shells of genuine escargot, however, most of the people eating the African snails are effectively deceived.
Giant African Land snails have an undeserved reputation that they can cause life-threatening infection like serious meningitis in humans. The only way humans have contracted eosinophilic meningoencephalitis disease is by eating the GAS raw, certainly not by handling the snail.
In the wild roughly 10% of GALS are infected by Angiostrongylus cantonensis, also known as a rat lungworm, but in areas with high rodent densities, this can be as high as 50%. If infected, they remain infected for life.
The indirect life cycle of the rat lungworm requires an intermediate host (usually a mollusk) for the development of various larval stages. The adult worms live in the pulmonary arteries and/or the right side of the heart of a rodent definitive host. Eggs laid in the pulmonary artery lodge themselves in the small lung capillaries where they develop into first stage larvae. The mobile first stage larvae migrate into the alimentary tract and pass in the rodent’s faeces. Numerous molluscs, and most commonly land snails and slugs serve as intermediate hosts. The first-stage larvae gain access to the snail/slug either by direct tissue penetration or ingestion of infected rodent faeces. These larvae moult twice in the mollusc muscle tissue where they become second and third-stage larvae. Third stage larvae are considered the “infective” stage and remain encysted in snail muscle tissue for the life of the mollusc or until eaten by a host. In humans, the development of the third stage larvae stalls in the brain, where they die and serve as the source of infection.