Shrimp study could lead to lighter military body armour

The fist-like club of the mantis shrimp, or stomatopod, accelerates rapidly under water and repeated blows can destroy mollusc shells and crab exoskeletons, both of which have been studied for decades for their impact-resistant qualities.

However, David Kisailus, an assistant professor at the University of California, Riverside’s Bourns College of Engineering, is interested in what enables the club to withstand 50,000 high-velocity strikes on prey during its lifespan.

Kisailus and colleagues from Nanyang Technical University, Brookhaven National Laboratory and Gonzaga University found that the club is a highly complex structure, comprised of three specialised regions that work together to create a structure tougher than many engineered ceramics. Their findings are published in Science.

According to a statement, the first region, located at the impacting surface of the club, contains a high concentration of mineral, similar to that found in human bone, which supports the impact when the mantis shrimp strikes prey.

Further inside, highly organised and rotated layers of chitin fibres dispersed in mineral act as a shock absorber, absorbing energy as stress waves pass through the club.

Finally, the club is encapsulated on its sides by oriented chitin fibres, which wrap around the club, keeping it intact during these high-velocity impacts.

‘This club is stiff, yet it’s lightweight and tough, making it incredibly impact tolerant and, interestingly, shock resistant,’ Kisailus said.

Kisailus said the potential applications in structural materials are widespread: with electric cars, less weight will reduce power consumption and increase driving range; and with aircraft, less weight would reduce fuel costs and better impact resistance would improve reliability and reduce repair bills.

Kisailus, however, is primarily focused on improving military body armour, which can add 30lb (14kg) to a soldier’s load. His goal is to develop a material that is one third of the weight and thickness of existing body armour.

To that end, Kisailus and Purdue University’s Pablo Zavattieri have received additional funding worth $590,000 (£382,000) from the US Air Force Office of Scientific Research to continue work on the stomatopod.