Crabs inspire scientists to build tough, tiny tools

February 26th, 2009 - 4:24 pm ICT by IANS  

Washington, Feb 26 (IANS) Scientists are taking inspiration from crab claws to build tiny tools, with a bromine rich biomaterial that is tougher than acrylic glass and extremely fracture resistant.
Crab claws and legs, tipped with bromine-rich material, is a new member of a class of structural biomaterials that employ heavy atoms like zinc, iodine and iron. The University of Oregon (UO)-led study is part of effort to tap nature’s secrets for building futuristic tools.

“It’s not yet clear why heavy elements are used,” said Robert Schofield, co-author of the study and Oregon physics researcher. “Perhaps the mass of the atoms themselves plays a role in damping vibrations that can lead to fracture.”

These heavy-element biomaterials had escaped notice until now because they are typically employed by small organisms such as insects. Schofield had co-authored a study in 2001 that had identified their presence in mandibular teeth, tarsal claws, stings and other such tools of small organisms.

Residents on the US west coast may have had close encounters with the biomaterial - detailed by the seven-member research team. The translucent substance empowers the claw tips of the striped shore crab as the pincers pick and hold prey.

It also is present on the walking legs of Dungeness crabs, a dining delicacy in the Pacific northwest. “The next time you are eating a Dungeness crab, notice that the sharp tip of the leg is a cap of translucent material that is very different from the rest of the crab,” Schofield said.

“Notice how difficult it is to break the tip, even though it is very thin. This biomaterial can bend six times further before breaking than the material used in other regions. If the tip were made of the same material as the rest of the crab, it could never stay sharp and the crab would have difficulty clinging.”

“The types of crabs that use this trick for their claw tips rely on the tips fitting together like forceps in order to pick and hold bits of food, and fracture damage could make the tips useless,” said Schofield, according to an UO release.

The claws of the Dungeness crab, he noted, are designed for crushing instead of fine manipulations, and are not tipped with this material. But their legs are, he said.

These findings were published online in the Journal of Structural Biology.

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