Structural and material design of mature mineralized radula teeth of Patella vulgata (gastropoda)

The molluscan radula is a cutting apparatus employed in feeding. It is a toothed ribbon located in the mouth cavity. This study focuses on the characterization, organization, and hardness of the various components in full grown, mineralized, radula teeth of the common limpet Patella vulgata. Three major components are identified: Fibrous organic material, acicular crystals of goethite (α-FeOOH), and silica (SiO₂). Each forms a coherent network intertwined with the other two. The goethite crystals lie parallel to the fibers in the organic framework. The orientations of fibers and crystals are described in detail. The hardness of the leading part, i.e., the part that leads in the cutting direction, is about twice the hardness in the trailing part. It is argued that this difference results from the greater compactness of the mineral matter in the leading part. The function of the tooth as a cutting device is discussed on the basis of the data presented in this study.