Does the mantis shrimp pack a phononic shield?

The powerful strikes generated by the smasher mantis shrimp require it to possess a robust protection mechanism to withstand the resultant forces. Although recent studies have suggested that phononic bandgaps complement the mantis shrimp's defensive suite, direct experimental evidence for this mechanism has remained elusive. In this work, we explored the phononic properties of the mantis shrimp's dactyl club using laser ultrasonic techniques and numerical simulations. Our results demonstrate that the dactyl club's periodic region functions as a dispersive, high-quality graded system, exhibiting Bloch harmonics, flat dispersion branches, ultraslow wave modes, and wide Bragg bandgaps in the lower megahertz range. These features effectively shield the shrimp from harmful high-frequency stress waves generated by cavitation bubble collapse events during impact.