Sept. 18 (UPI) -- The teeth of the pink sea urchin never get dull, according to a new study that determined the creatures boast teeth that sharpen themselves.
At the center of the pink sea urchin's spiked, globular body are five teeth, each anchored to a separate jaw. Unlike the teeth of most other animals, which either withstand wear or fall out and are replaced, the sea urchin's teeth sharpen themselves.
A close examination of a sea urchin tooth showed it is designed to maintain a sharp edge as fragments of the tooth get chipped away. It is as if fault lines are built into the tooth's structure to ensure as bits break away, the edge is maintained.
"The material on the outer layer of the tooth exhibits a complex behavior of plasticity and damage that regulates 'controlled' chipping of the tooth to maintain its sharpness," Horacio Espinosa, researcher at Northwestern University, said in a news release.
The ceramic materials of a sea urchin tooth are brittle, which makes the ability to selectively chip all the more surprising.
For the study, published Wednesday in the journal Matter, scientists used electron microscopy to film sea urchin teeth undergoing sophisticated mechanical testing. The slow-motion, 3D movies helped scientists understand how the ceramic material breaks down.
The footage showed the teeth are composed of specially arranged ceramic composites. Calcite fibers located on the convex side of the tooth offer structural integrity. The fibrous composites are adjoined to a series of inclined calcite plates on the other side of the tooth, the convex side. When exposed to mechanical stress, the plates chip away, which allows the tooth to maintain its edge.
Scientists hope their research will be used to develop synthetic materials that can be used in tools for tasks that require cutting, grinding or boring.
"I am exploring ways to do additive manufacturing of materials that can exhibit the performance of natural materials," Espinosa said.