This study examines the possiblility that the physical properties of pedal mucus limit the size and speed of gastropods. At small deformations hydrated pedal mucus is a viscoelastic solid. At large deformations the mucus yields and becomes a viscous liquid, the yield strength increasing as the rate of deformation increases. The mucus can ‘heal’ if left undeformed, its strength increasing with time. When dehydrated the mucus strength and stiffness increase substantially. These properties can be used to calculate the maximum speed of crawling and the maximum size for gastropods. In all the cases examined the predicted maxima are near those observed in nature, and it seems likely that pedal mucus indeed places limits on gastropod structure and performance.

Author notes

1From the Symposium on Biomechanics presented at the Annual Meeting of the American Society of Zoologists, 27–30 December 1982, at Louisville, Kentucky.