Some molluscs and their fossils entered in ancient myths and legends in the culture of many peoples. The most famous of them is the kraken, the legendary sea monster that sailors believed capable of attacking and sinking ships. Today, we know that giant squids (Architeuthis) really exist in the depths of the oceans, buttheir meetingis very rare.
If we exclude the myths, few truly dangerous molluscs exist: nevertheless, some species should be handled with extreme care, like the venomous cones or few species of tropical octopuses.
There is no known bivalve dangerous in itself, but they can, if ingested, become poten-tial carriers of pathogens and toxins, causing intestinal disorders and intoxications. Moreover, some terrestrial and freshwater gastropods, especially in tropical areas, are intermediate hosts in the complex life cycles of many flatworm parasites of man, such as flukes and tapeworms. Absolutely innocent, these small gastropods are carriers of se-rious diseases such as fascioliasis.
Some marine bivalves, like ship-worms (Teredo), are able to drill, using acid secretions, wood, claysand carbonate substrates, whose action cannot be underestimated, because it has often resulted in serious damage.
Some land snails and slugs, when introduced into alien environments where there are no natural predators, can create real havoc. The giant African snail (Achatina) is a very ag-gressive pest. In general, many snails are harmful to agriculture, because they attack the more tender parts of plants useful to man, and they can also spread infectious diseases between horticultural plants.
Keywords: Achatina, Aplysia, Architeuthis, bilharzia, blue-ringed octopus, Conus, kraken, Fasciola, Glaucus, Hapalochlena, harmful algal blooms, Lymnaea, opis-thorchiasis, paragonimiasis, paralytic shellfish poisoning, Scylla, ship-worm, Te-redo, Tridacnagigas.