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Garden SnailsHermaphrodites Who Spear Their Partners During Courtship
Deliberately introduced into Britain and America for eating, but now agricultural pests.
The Garden Snail (Helix aspersa) was introduced into Britain (from Italy) many years ago, by the Romans in the first century AD – or possibly even earlier – and it was introduced into the USA in the nineteenth century, probably by French immigrants. In both cases these snails were intended for the table but have gone on to become serious agricultural pests. Snail as FoodHelix aspersa is very adaptable species, and it is now farmed in many countries to provide a steady supply for the table. Each country and region seems to have its own preferred ways of cooking snails, but some features of preparation remain constant. Before they are cooked snails need to be washed and given a few days to empty their intestines, and then they need to get rid of some of their slimy mucus. They are often kept in wooden cages for the cleaning period, and brine or salt seems to persuade them to ‘de-slime’. They can then be cooked and eaten. (Preparation and Recipes) Snails as PestsAny introduced species of animal loses many of its natural predators (such as the Decollate Snail in this case) when it arrives in a new country. Garden Snails will eat almost any vegetable material and without this sort of natural control they have become serious pests in America, particularly in California. While it is a nuisance to gardeners in Britain the situation is less serious. There has probably been long enough since their introduction thousands of years ago for natural predators to put them on their ‘food list’! Sex LifeLike their relatives (slugs) Garden Snails are hermaphrodites. This means that are both fully functional males and fully functional females. An individual snail cannot fertilise itself, so it needs to find a partner – but anyone will do! They exchange sperm with this partner and then use the received sperm to fertilise their own eggs inside their body. Eggs are laid in the soil and hatch as very small snails which take a couple of years to reach maturity. The courtship is bizarre to say the least. Love DartsAn important part of the courtship of snails involves the exchange of ‘Love Darts’. After a period of mutual stroking, twining and generally crawling all over one-another the excited snails hurl chalky darts into their partner’s head. (These darts are about half an inch long – but that’s big if you are a snail.) At one time it was thought that the ‘gift’ of Calcium Carbonate helped the partner form eggs, but it now looks as if the mucus covering of the ‘Love Dart’ is more important. Research has shown that chemicals in this mucus covering increase reproductive success, probably protecting the exchanged sperm in some way. Other articles by John Blatchford
The copyright of the article Garden Snails in Other Invertebrates is owned by John Blatchford. Permission to republish Garden Snails in print or online must be granted by the author in writing.
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