Researchers at Northwestern University have uncovered how mantis shrimp withstand the powerful shockwaves generated by their own strikes. Known for their ability to smash shells with force comparable to a .22 caliber bullet, these creatures remain undamaged due to unique structural features in their dactyl clubs.
The study, set to be published in the journal Science, reveals that the mantis shrimp's clubs are covered in layered patterns that selectively filter out sound. This pattern acts as a shield against self-generated shockwaves, potentially inspiring new materials for protective gear and methods to reduce blast-related injuries.
Horacio D. Espinosa, co-corresponding author of the study and a professor at Northwestern’s McCormick School of Engineering, explained: “The mantis shrimp is known for its incredibly powerful strike... However, to repeatedly execute these high-impact strikes, the mantis shrimp’s dactyl club must have a robust protection mechanism to prevent self-damage.” He noted that previous research focused on toughness and crack resistance but found that phononic mechanisms play a crucial role in filtering stress waves.
Espinosa collaborated with M. Abi Ghanem from France's Institute of Light and Matter on this research. They used advanced techniques like transient grating spectroscopy and picosecond laser ultrasonics to analyze the shrimp's armor. Their findings identified two distinct regions within the club: an impact region with mineralized fibers arranged in a herringbone pattern for resistance and a periodic region with corkscrew-like fiber bundles forming a Bouligand structure.
These structures help manage stress waves effectively. “The periodic region plays a crucial role in selectively filtering out high-frequency shear waves,” Espinosa said. The study suggests further exploration through 3D simulations and aquatic experiments could enhance understanding of these mechanisms.
Supported by various scientific organizations including the Air Force Office of Scientific Research and the National Science Foundation, this research offers promising insights into bio-inspired protective materials.