Bioceramics propel the famous mantis shrimp punch

Researchers in Singapore can now explain what gives mantis shrimp, a marine crustacean that hunts by prey hunting with its club-shaped appendages, the most powerful punch in the animal world. In a newspaper published on October 19 in the journal iScience, they show that a saddle-shaped structure in mantis shrimp members, which acts as a source for storing and then releasing energy, is composed of two layers made of different materials. Measuring the composition and micromechanical properties of the bioceramic and biopolymer layers, for the most part, allowed researchers to simulate how the saddle stores large amounts of elastic energy without breaking.

"Nature has developed a very clever design on this saddle," says lead author Ali Miserez, a materials scientist who studies the unique biological structures of Nanyang Technological University in Singapore. "If it was made of a homogeneous material, it would be very fragile, it would break for sure."

Past research by biologist Sheila Patek had examined the mantis shrimp mantis – the appendages they use to attack their prey – and suggested that the muscles alone could not create the force with which the crustaceans hit. Other research had hypothesized that the saddle could be used to store elastic energy, but it was difficult to study the structure and mechanical properties of the saddle. "The movement is so fast that people have not been able to focus solely on the stool itself, that's why we had to study it by computer simulation," he said. declared Miserez.

His team analyzed the composition of the saddle and made micro-measurements of the mechanical properties of the materials in order to develop a simulation of the striking of mantis shrimps. They found that the upper layer of the saddle is composed mainly of relatively fragile bioceramic, similar to the tooth or bone, while the underside contains a larger amount of biopolymers, which are fibrous like a rope and are therefore resistant to traction. When the muscles and connective tissues of mantis shrimp load energy in the saddle, the upper layer is compressed and the lower layer is stretched, which means that each layer is placed under the forces that it supports the best.

"If you asked a mechanical engineer to make a spring capable of storing a lot of elastic energy, he would not think of using a ceramic.The ceramic can store energy if you can deform it, but she is so fragile that she would not be intuitive, "says Miserez. "But if you compress them, they're strong enough, and because they're stiffer than metal or any polymer, you can store more energy than you can with these materials." . "

The researchers also performed a series of experiments using small strips of real saddle structures that they cut with a powerful picosecond laser beam. They analyzed how the forces were distributed when the bands were folded as they are in the mantis shrimp and when they were bent the wrong way. When folded upside down, with compressed biopolymers and stretched bioceramics, the bands were less able to withstand significant forces, probably due to tiny fractures in the ceramic layer.

Miserez and his colleagues continue to study the saddle structure of mantis shrimp and have even begun to print in 3D sources inspired by mantis shrimp, which could possibly be used in microrobotics.

"From a basic scientific point of view, the mechanisms of this structure are very interesting," he says. "But this design also shows that you can create a very effective spring – and that you can make it ceramic, which is more efficient than other materials that people are using now." You can use materials that you do not want to use. have not thought, based on your knowledge of mechanical engineering.

Explore further:
How shrimp mantis evolved many shapes with the same powerful punch

More information:
Tadayon et al .: "Biomechanical Design of Mantis Shrimp Saddle – A Biomineralized Spring Used for Raptorin Rapid Strikes" iScience (2018). DOI: 10.1016 / j.isci.2018.08.022