Introduction

Molluscs are an ancient group of animals which originated during the Palaeozoic era some 500 million years ago. They are the second largest phylum of animals and can be recognised as they usually have a shell protecting the soft body. There are an estimated 80,000 described species, with many species still undescribed.

There are six classes of Mollusca:

• Gastropoda, includes species from marine, freshwater and terrestrial environments (including slugs),
• Bivalvia (mussels, oysters),
• Cephalopoda (octopus, squid, cuttlefish),
• Scaphopoda (tusk shells),
• Amphineura (chitons),
• Aplacophora - are mainly fossil, but one genus has been found living in deep ocean muds.

People who work on Molluscs are either 'Malacologists' on 'Conchologists'. Malacology is the study of the whole animal, whereas Conchology is the study of their shells.