According to Hutchinson Unabridge Encyclopedia, snails are air-breathing gastropod mollusc with a spiral shell. There are thousands of species, on land and in water. The typical snails of the genus Helix have two species in Europe. The common garden snail H. aspersa is very destructive to plants.
Snails are hermaphrodite and, before mating, produce a mucus covered calcerous ‘love dart’ that pierces the skin of their mate. The mucus contains a pheromone that makes the female reproductive canal less hostile to sperm.
Self-fertilization is very common in snails.
The Roman snail H. pomatia is ‘corralled’ for the gourmet food market. Overcollection has depleted the population. The French eat as much as 5 kg/11 lb of snails a head each year.