From the knitting shop: the first physical and dynamic model of the taenioglossan radula (Mollusca: Gastropoda) aids in unravelling functional principles of the radular morphology

The radula is the structure used for food processing in Mollusca. It can consist of a membrane with stiffer teeth, which is, together with alary processus, muscles and odontophoral cartilages, part of the buccal mass. In malacology, it is common practice to infer potential tooth functions from morphology. Thus, past approaches to explain functional principles are mainly hypothesis driven. Therefore, there is an urgent need for a workflow testing hypotheses on the function of teeth and buccal mass components and interaction of structures, which can contribute to understanding the structure as a whole. Here, in a non-conventional approach, we introduce a physical and dynamic radular model, based on morphological data of Spekia zonata (Gastropoda, Paludomidae). Structures were documented, computer-modelled, three-dimensional-printed and assembled to gather a simplistic but realistic physical and dynamic radular model. Such a bioinspired design enabled studying of radular kinematics and interaction of parts when underlain supporting structures were manipulated in a similar manner as could result from muscle contractions. The presented work is a first step to provide a constructional manual, paving the way for even more realistic physical radular models, which could be used for understanding radular functional morphology and for the development of novel gripping devices.