This shrimp ain't weak! |

I had heard and learned many times how studying other species affords knowledge that enables humans to do things better- or even do things we never thought possible.

And, that’s exactly what Dr. D. Kisailusa’s (Chem E, UC Riverside, corresponding author) group [the rest of the group was comprised of Riverside’s Drs. Grunefeldera, Salinasa, Milliorn, Yaraghic, Herreraa, Evans-Lutterodtd, Nutte, along with Purdue’s Drs. Suksangpayab and Zavarrierib] did. In an article published in Acta biomaterialia, they presented their findings concerning the peacock mantis shrimp. This creature has the “fastest fists in the west”, and with the hardest “mitts” we’ve seen. It’s claws have a shock-absorbing interiors, with durable and strong exteriors.

These shrimp (they are only about 2 inches long) corner their prey (typically against rocks) and beat them to death, opening their shells or skulls. (These shrimp actually need to be contained in plastic aquaria, because they can break the glass in conventional structures.) Their muscles act like the bow- launching their fists in rapid bursts, hitting their targets. (Forget the blink of an eye- that’s about 50X slower than their fists.)

These claws move so quickly, they actually cause cavitation. The water about their claws virtually boils- and when those bubbles collapse, the resulting shock wave augments the shrimp’s actions by fracturing and rupturing the target animal’s bone structures.

What makes them so strong? There a fibrous layers of chitin (the substance found in the exoskeletons of insects and crustaceans), with interstitial calcium carbonate and calcium phosphate. (Interstitial means between the cracks or fibers of chitin.) Moreover, these fibers are arranged in a helicoidal (like a corkscrew) fashion. Each ascending layer of chitin is slightly askew of the lower layer (horizontally rotated). As such, the structure is able to withstand significant impact energy/forces. Any cracks that do form can’t travel from one layer to the next, due to the helicoidal arrangement.

Dr. Kisailus’ group was able to mimic this architecture (with an angle of about 15 degrees from one layer to the next) using carbon fibers with epoxy in the interstices. When arranged in the helicoidal fashion, these structures were much stronger than unidirectional structures or with 45 degree rotated fibers (which are standard ise in the aircraft industry; they are called quasi-isotropic arrangements).

Dropping a weight vertically upon the unidirectional structure caused immediate and irrevocable failure- the structure simply ruptured into two parts. The quasi-isotropic (QI) version of the structure let the weight puncture the layers to the bottom layer. The helicoidal system was damaged- but 49% less dented than its QI cousin. Basically, the helicoidal structure dissipates the energy that can cause damage laterally, rather than vertically.

If all goes well, the structural carbon fibers made that mimic this structure will find their way into aircraft panels, body armor, and helmets.