The dentition of the gumboot chiton, a lumbering mollusk, contains a rare mineral never before seen in a living animal. …
The gumboot chiton is not a glamorous creature. The large, lumpy mollusk creeps along the waters of the Pacific coast, pulling its reddish-brown body up and down the shoreline. It is sometimes known, not unreasonably, as “the wandering meatloaf.” But the chiton’s unassuming body hides an array of tiny but formidable teeth. These teeth, which the creature uses to scrape algae from rocks, are among the hardest materials known to exist in a living organism.
Now, a team of scientists has discovered a surprising ingredient in the chiton’s rock-hard dentition: a rare, iron-based mineral that previously had been found only in actual rocks. Tiny particles of the mineral, which is strong but lightweight, help harden the root of the mollusk’s teeth, the researchers reported in the journal PNAS on Monday.
The discovery could help engineers design new kinds of materials, according to the scientists, who provided proof-of-principle by creating a new chiton-inspired ink for 3-D printers.
A chiton feeds by sweeping its flexible, ribbonlike tongue, known as a radula, along algae-covered rocks. Its ultrahard teeth are arrayed in rows along the soft radula. A long, hollow tube, known as the stylus, anchors each tooth to the radula.
Scientists had previously discovered that the tops of chiton teeth contained an iron ore called magnetite, but knew less about the composition of the stylus. “We knew that there was iron in the upper part of the tooth,” said Linus Stegbauer, a material scientist at the University of Stuttgart, in Germany, and the paper’s first author. “But in the root structure, we had no idea what is going on in there.”
