Last updated January 17, 2018 at 4:10 pm
The structure of the mantis shrimp’s deadly hammer claw provides inspiration for advanced super-strong protective materials in aerospace and sport applications.
The mantis shrimp knows how to look after itself. Credit: iStock
The mantis shrimp is known as the ocean’s heavy-hitter. It has a hammer-like club that moves with the speed of a .22 calibre bullet and strikes with the force of 1,500 newtons – enough to smash the glass of an aquarium – that pulverises its prey.
Until now, scientists have not known how the animal does this without injuring itself, but a new study shows that the hammer is bound with unique structure that protects it rather in the way binding protects a boxer’s hands.
A series of highly aligned fibres wrap around the club and stop it from expanding upon impact.
Then researchers hope the finding will in future lead to the development of ultra-strong materials for the aerospace and sports industries.
“We believe the role of the fibre-reinforced striated region in the smasher’s club is much like the hand wrap used by boxers when they fight,” explains research leader David Kisailus from UC Riverside. “To compress the club and prevent catastrophic cracking.
“Together, the impact, periodic and striated regions form a club of incredible strength, durability and impact resistance.”
A cross-section of the mantis shrimp club shows the striated region that was characterised by UCR researchers. This region comprises a unique structure that wraps around the club to protect it from self-inflicted damage as the mantis shrimp crushes its prey. Credit: UC Riverside
The same team in earlier research showed that the smasher – officially known as the dactyl club – is made of a multi-regional composite made of mineralised chitin, the same material found in the shells of insects and crustaceans, arranged in a number of unique structures.
They found the interior of the club is made up of two regions: the periodic region, an energy-absorbing structure that dissipates cracks along a series of long helicoidal (spiral-like) fibres, and the striated region – the subject of the current study.
Mantis shrimp, which are also called stomatopods, are divided into two groups: the “smashers” and the “spearers”. The latter attack soft-bodied prey using a harpoon-like structure, while the smashers concentrate on hard-shelled prey.
The attack limbs can move at speeds of up to 23 metres per second thanks to the hydrodynamic teardrop design that reduces resistance. The hammer moves so fast that it creates a stream of bubbles that it creates vapour-filled bubbles – called cavitation bubbles – that collapse to provide a secondary impact on the mantis shrimp’s prey.
“Aerodynamic cycling helmets and golf clubs already incorporate this design, suggesting that nature was one step ahead of humans in achieving high performance structures,” Kisailus said.
“The natural world can provide many more design cues that will enable us to develop high performance synthetic materials.”
The research was published today in Advanced Materials.
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