ABSTRACT
This chapter provides an overview of the external body of molluscs, comprising the mantle, the shell and its formation and growth, the epidermis and associated structures, the foot and operculum, mucoid secretions, locomotion, and general information on cartilage and muscles. Molluscan shells have attracted the interest of a wide range of scientists from many disparate disciplines as well as naturalists, artists and collectors, and the public. Molluscs move by crawling, burrowing, or swimming. In those that crawl or burrow, and in some that swim, the foot is the main organ of locomotion. The muscles involved in the movement of the mouth, buccal cavity, and the odontophoral apparatus comprise the most complex set of muscles in the body. Adductor muscles are the muscles that pull the valves together in a bivalved shell. Retractor muscles perform a variety of functions including locomotion, feeding actions, reproductive behaviour, and retraction of a body part away from tactile stimuli.
