The Mechanism of Locomotion in Gastropod Molluscs

Whereas the broad outline of the mechanical events of locomotion can in most animals be readily visualized, the mechanism of propulsion in gastropods is less easily observed. Since the seventeenth century (Lister, 1694) a great deal of attention has been paid to this problem and a wealth of suggestions has been forthcoming; there is, however, a significant absence of convincing experimental data. To some extent the problem is confusing on account of the diversity of locomotory mechanisms existing within the group (Vies, 1907; Parker, 1911; Olmsted, 1917; Weber, 1925). Nevertheless, there can be no room for doubt that one characteristic type of movement depends upon the propagation of waves of muscular activity over the surface of the animal's foot. So far as is known, no adequate account has yet been, given of the method whereby this type of activity propels the animal over the surface of the ground. The present paper deals with these problems in respect to three representative genera, Helix, Haliotis and Pomatias.