Chitons and Nanotechnology

Cryptochiton stelleri, (aka the “gumboot chiton”, or “the wandering meatloaf”)

Chitons are back in international headlines again! Or, to be more technically accurate, the overlooked armored mollusks at least made it into the news (perhaps for the first or second time in their 400-500 million year history). These remarkable miniature tanks consist of a muscular mollusk which lives encased in 8 interlocking pieces of hard aragonite armor. The armor is not only a shell–it contains integral parts of the chiton such as aragonite eyes and other sensory cells. Thanks to this robust design, chitons are extremely successful and they can be found living in intertidal zones worldwide. Although they lack the pizzazz of their flamboyant mollusk cousins such as bobtail squid or giant clams, chitons are of enormous interest to a new generation of materials scientists who have been studying the natural world to get fresh ideas for molecular engineering. This weekend’s news story comes from such scientists who discovered that a brown rectangular chiton, Cryptochiton stelleri, (aka the “gumboot chiton”, or “the wandering meatloaf”) contains an esoteric mineral named santabarbaraite never before found in a living creature. Santabarbaraite is an extremely hard and tough mineral (itself only discovered by scientists in the year 2000) which contains a surprising amount of water. In the parlance of chemists, it is an amorphous ferric hydroxy phosphate mineral hydrate. The gumboot chitons manufacture this material as part of their long rows of rock-hard teeth (with which they scrape algae from marine rocks). Coincidentally, gumboot chitons are the largest chitons out there, with a maximum possible length of 36 centimeters (14 inches).

The teeth of the gumboot!

This is undoubtedly fascinating to people with advanced understanding of the chemical structures and properties of matter, but it is somewhat abstruse. The study’s lead author, scientist Derk Joester of Northwestern helps contextualize the importance of the finding by noting that “mechanical structures are only as good as their weakest link, so it’s interesting to learn how the chiton solves the engineering problem of how to connect its ultrahard tooth to a soft underlying structure.” The researchers are already planning how to use the secrets they have gleaned from the chiton to print hard santabarbaraite structures onto soft papers.

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