Piranha have a well-earned reputation for being able and willing to eat just about anything in their path. One of the few exceptions is the Arapaima, a six-foot long, 300-pound Amazonian predator with bony scales capable of withstanding the toothy onslaught. Researchers are now working to adapt the Arapaima's defenses to protect our own squishy bits.
You'd think a fish the size of an offensive lineman would be able to get by on bulk alone. But, during the dry season, Arapaima are forced to share dwindling pools with the voracious piranha. Its durable scales are what keep the Arapaima intact until the waters rise again.
Its scales are composed of a hard, corrugated outer layer over a pliable layer of collagen. What's more, the fibres that make up the outer layer are arranged in alternating directions -- like a parquet floor. This allows the scales to flex as the fish swims and spreads a piranha's bite force out over a larger area, preventing the piranha's teeth from penetrating.
Researchers from UC San Diego, lead by mechanical and aerospace engineering professor Marc Meyers, hope to replicate this "hard on the outside, soft on the inside" system to create bendable ceramics. Conventional ceramics are very hard and quite durable but lose that strength when forced to curve around an object. Corrugation allows the plate to bend without cracking.
"The materials that nature has at its disposal are not very strong," said Meyers, "but nature combines them in a very ingenious way to produce strong components and strong designs." The research team hopes to develop these durable-yet-flexible plates to one day replace the conventional flat plating in soldiers' body armour. [UC San Diego via Gizmag]