Bodies of molluscs are subdivided into three parts:
*The head that contains the sensory organs and the mouth that contains the radula and odontophores (absent in bivalves).
*The foot is a muscular organ, typical of molluscs, intended for locomotion. It has different shapes depending on the species.
*The visceral mass, as the name suggests, contains the viscera. It is contained in a thin tunic called the coat. It is the mantle that secretes the shell of most molluscs, which serves as protection and / or skeleton and / or regulator of flotation.
Between the mantle and the visceral mass, the pallial rim constitutes a pallial cavity that protects the respiratory organs, and where the metanephridia (excretory organs), the intestine and the genital ducts open.
