Meeting Abstract
Raja binoculata, the largest skate species of North America, inhabits the ocean bottom from the marine intertidal to the continental shelf, where it feeds on shellfish, worms and crabs. For crushing hard shelled prey the teeth of big skates need to be well supported by the jaws. The jaw suspension is euhyostylic, which means that the upper jaws are not directly connected to the cranium giving them more freedom of movement, and the hyoid is broken up. Moreover, the jaws are composed of tessellated cartilage, which inspired us to look closer at its biomechanical properties. In this study, we used mechanical testing (E-modulus, flexural stiffness, strength), microscopical methods in combination with specialized calculations (minaralization, second moment of area), 3D scanning and 3D printing to investigate how R. binoculata crushes hard shelled prey. Our results for the second momet of area and flexural stiffness show that the shape of the jaws is strongly optimized to withstand crushing forces. In addition to quantifying compressive strength, strain and E-Modulus of the jaw elements of R. binoculata, we investigated the effect of the irregular shape of the cartilage elements on the mechancial variables. In contrast to engineered shapes, biological shapes are not standardized along geometric paramenters and as composite materials can not be modified into one for testing. Nevertheless, biologists use the same methods to measure biomechanical parameters to assess the performance of biological shapes. Using 3D-prints of synthetic material similar to cartilage, with the same shape as the jaw elements, we found that shape can impact the measured values of biomechanical properties.
