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The Incredible Anatomy of Mantis Shrimp: Nature’s Engineering Marvel

Mantis shrimp are renowned for their extraordinary ability to deliver rapid and forceful strikes to capture prey. These remarkable creatures can unleash a succession of punches that crack shells without suffering any significant damage to their own bodies.

Research published on February 7 in Science suggests that the unique design of their club-like forelimbs plays a crucial role in allowing them to withstand the intense physical forces they generate. The exoskeleton of these limbs is engineered to absorb damaging pressure waves from their powerful strikes.

Despite their small size, peacock mantis shrimp (Odontodactylus scyllarus) are capable of striking with such speed that they generate imploding bubbles. The combined effects of the impact and the resulting bubble implosion can create forces that surpass 1,000 times the mantis shrimp’s weight. Remarkably, they are able to repeat these strikes without any harm to their limbs.

Researchers previously hypothesized that the structural design of the club’s exoskeleton was responsible for this resilience. The outer layers are made of mineral-hardened chitin, a polysaccharide that forms the primary component of arthropod exoskeletons. This outer layer rests above a complex arrangement of chitin bundles, which are slightly rotated in relation to each other, resembling a twisted stack of paper—known as a Bouligand structure.

While it was believed that this design could effectively manipulate the propagation of high-energy waves, thorough experimental validation was lacking.

“Most of the earlier understanding was based on theoretical models,” noted Hortense Le Ferrand, a material scientist and engineer at Nanyang Technological University in Singapore, who was not part of the study. Some experts in bioengineering had expressed skepticism due to the absence of conclusive evidence supporting these claims.

In an effort to explore this further, Horacio Espinosa, an engineer from Northwestern University, and his team conducted a series of laboratory experiments. They simulated the pressure waves experienced by the mantis shrimp by firing laser pulses at samples of their club exoskeleton. This process rapidly heated and expanded the material, allowing researchers to examine how the created high-energy waves propagated through it.

The findings revealed that the mineralized outer layers of the exoskeleton effectively control the spread of small cracks generated from impacts, while the deeper helix-like layers dissipate and neutralize high-energy waves. This dynamic interaction “prevents shear waves from damaging the soft tissue within the club,” explains Espinosa.

Interestingly, the structural design of the mantis shrimp’s club mirrors some engineered materials specifically designed to control sound wave propagation. Federico Bosia, a physicist at the Polytechnic University of Turin in Italy, emphasized that this observation underscores the natural occurrence of such designs in biological systems, which have evolved over time for purposes of wave and vibration management. He notes that other natural examples, such as the wing scales of certain moth species, also possess sound-dampening properties to evade detection by bat echolocation.

According to Espinosa, the architectural features of the mantis shrimp’s exoskeleton could pave the way for innovative applications in creating impact-resistant armor, protective coatings, and aerospace technologies.

David Kisailus, a materials scientist at the University of California, Irvine, is already utilizing the unique helix structures inspired by the mantis shrimp to improve the durability of airplane wings, wind turbine blades, and hockey sticks. Kisailus believes that the discoveries surrounding the mantis shrimp are just the beginning, with countless other organisms waiting to reveal their own ingenious adaptations.

“Nature has millions of species that have evolved to meet varied challenges,” Kisailus remarked. “There are many biological blueprints in nature’s treasure trove just waiting to be discovered.”

Source
www.sciencenews.org