What is a mollusc?

Samples of molluscs

The words 'mollusc' is derived from the Latin word mollis meaning 'soft'. Molluscs include all the shelled creatures of the seashore, with the exception of the barnacles and land creatures like the snail and bivalves. Creatures like the octopus, jellyfish and slugs are molluscs that don't have shells.

Molluscs form one of the largest groups in the Animal Kingdom. Over 160,000 species have been described, of which around 128,000 are living and about 35,000 are recorded as fossil species.

Moluscs have similar characteristics in that they have an unsegmented soft body, most have an internal or external shell, they have a mantle (fold in the body wall that lines the shell) and a muscular foot and/or tentacles.