Locomotion in Mollusca
The major locomotor organ in Mollusca is the foot, which is a characteristic feature of these animals. In its simplest form the foot is a flit ventral sole that is best suited to secure attachment and progression of body by creeping. As coelom extremely is reduced, it is not significant as a hydrostatic skeleton in this group of animals. Conversely, the foot is muscular and is provided with cilia and mucus cells. With this, the hydrostatic properties of blood system make it an excellent organ of locomotion. In bivalves, shell as well plays an important role in locomotion. The foot as well exhibits a wide diversity of forms to serve like an organ not only for crawling, but for burrowing, leaping and swimming as well. These activities are related to the environment and mode of living of the Mollusca. Let us see the various modifications of foot associated with the locomotor function in different groups of Mollusca.