Breaking force Spekia

One molluscan autapomorphy is the radula, the organ used for feeding.
Here, for the first time, the performance and failure of taenioglossan
radular teeth were tested in a biomechanical experiment which in turn
allowed building hypotheses about tooth functionalities. Shear load was
applied to tooth cusps with a force transducer until structural failure
occurred, the broken area was measured, and finally breaking stress was
calculated. These experiments were carried out under dry and wet
conditions. Our results show that certain tooth types can resist higher
stresses and are rather specialised to loosen food items from a surface,
whereas other teeth can only gather food particles. The experiments
additionally illustrate the high influence of the water content on the
resulting breaking stress. When wet teeth were tested, their ductility and
ability to avoid being fractured by an obstacle increased. Their
flexibility also allowed them support from teeth of adjacent tooth rows,
which made the whole system less prone to failure. Our results were
compared with the previous data on the mechanical properties and feeding
simulations. This study provides a keystone for further comparative
studies aiming at connecting diversity of radulae with their possible
adaptations to the ingesta.