1) Molluscs have soft, moist bodies covered in skin or a shell. They live mainly in water but some live on land like snails and slugs. 2) They are divided into three groups - gastropods, bivalves, and cephalopods. Gastropods have one shell and move slowly by muscle contraction. Bivalves have two shells. 3) Cephalopods like squid and octopus have tentacles around their mouth to catch prey.