The peacock mantis shrimp holds the Guinness World Record for the most powerful punch delivered by an animal using its own strength. (Photo by Reinhard Dirscherl/Getty Images)
Mantis shrimp pack a powerful punch, and scientists have finally figured out how this surprisingly powerful strike doesn't destroy the shrimp itself during an attack. It turns out that these shrimp have a special shock-absorbing “shield” that helps them withstand devastating blows to the shell.
The peacock mantis (Odontodactylus scyllarus) strikes with the most powerful independent punch of any animal. They use hammer-like fists or club-like fingers to smash the shells of their prey. The strike is so powerful that it can shatter aquarium glass, generating a force comparable to a .22 caliber bullet.
However, since these powerful strikes generate a significant amount of force, scientists have questioned how these creatures can withstand the intense shockwaves generated by their own attacks.
In a new study published Feb. 6 in the journal Science, researchers examined the structure of shrimp fists. Their findings showed that the microstructure of these fists functions as a natural shock absorber, reducing damage.
“We found that it uses phononic mechanisms — structures that selectively filter stress waves,” said study co-author Horacio Dante Espinosa, a professor of mechanical and biomedical engineering at Northwestern University. “This allows the shrimp to maintain its striking force after multiple impacts and prevents damage to soft tissue.”
Powerful blow
Peacock mantis shrimp use a complex system of biological latches and springs in their finger-like clubs to strike at speeds of 75 feet per second (23 meters per second) — 50 times faster than the blink of an eye, according to a 2004 study.
While this high speed allows for powerful strikes, it also creates dangerous shockwaves.
“The impact is so fast that it creates cavitation bubbles that collapse, producing additional shock waves, essentially creating a double impact,” Espinosa added.
Previous studies have suggested that the microstructure of the finger pins helps protect the shrimp from these shock waves.
In a new study, scientists tested this hypothesis by using advanced laser techniques to analyze how different wavelengths of light pass through the finger-like appendages of mantis shrimp.
The study's findings identified two key areas in these fists that help them cope with their own punches: the striking area and the periodic area.
The striking zone consists of a layer of chitinous fibers arranged in a herringbone pattern, which strengthens the fist and protects it from breakage.
Beneath this layer is a periodic region consisting of twisted arrangements of layered chitinous fibers. This type of helical structure is known as a Bouligand structure and is seen in fish scales and lobster exoskeletons, providing strength and resistance to fracture.
Laser tests measured the speed of acoustic stress waves through both regions. These waves passed through the shock zone unchanged, but moved at different speeds through the periodic region — indicating that the latter region causes the high-frequency waves to dissipate, reducing their intensity.
According to the statement, the researchers also found that the periodic region filters out high-frequency shock waves that can cause significant damage to tissue.
High frequency waves are likely generated by the collapse of cavitation bubbles.
“We linked this high frequency to the frequency generated when the bubble collapses during the impact,” Espinosa added.
The fiber bundles in the periodic region act as a “phonon shield,” actively blocking, redirecting, and cutting waves, which ultimately prevents any harmful shock waves from effectively passing through the layer. This protects the delicate tissues of the mantis shrimp from
Sourse: www.livescience.com
