A Wonder Of Nature: Chiton Teeth

Who do you think has the hardest teeth in the world? It’s not Jaws from the 007 films The Spy Who Loved Me and Moonraker, though he certainly may rank up there. Before you start thinking it’s a big cat or an elephant, one hint is…it doesn’t live on land.

Sharks might have the most vicious looking teeth under the sea. But the hardest set of teeth belong to the unassuming, slow, and snail-like mollusk called chitons.

Chitons form a class under the phylum Mollusca. Within this phylum we have all those creepy, slimy creatures that make us feel uneasy: giant squids, snails, slugs, etc. They’re not all bad. Clams, oysters, mussels, and scallops are grouped here too.

Mollusca make up 23% of all marine life. Far more than any other phylum. Molluscs are also incredibly ancient. They’ve been crawling around for over 400 million years.

Yet it’s not the longevity of the chiton we’re concerned with. It’s their teeth. Their magnificently crafted teeth. They’re made out of magnetite. It’s the hardest material created by a living organism.

In a lab, magnetite can be synthesized, but it’s hardly simple or easy. It requires very high temperatures and pressure in addition to a strongly acidic or basic setting.

Even with all our technology, making magnetite is grueling. Yet this simple, multi-million year old creature can create the material out of only the iron available in algae and in oceanic conditions. So how are chiton teeth made?

Lyle Gordon, a bioengineer at Northwestern University, used an atom probe to get a closer look. He and his team found a complex of protein and carbohydrates. The protein is negatively charged, grabbing the iron. The carbs are positive, attracting magnesium and sodium.

This network of proteins and carbohydrates form the magnetite shield that cover the teeth. It is a beautiful, natural, and almost mechanical type mechanism. As teeth get older, younger ones push them towards the tip like an assembly line.

Chitons ability to create such an incredible substance from so little and in changing conditions inspires Gordon to move forward. By further studying the chiton, he believes we could unlock secrets to make materials like silicon carbide and diamond cheaply.

But there’s a long road ahead. Gordon observed the protein-carbohydrate network that builds the teeth. He doesn’t, however, know the genes that code for the protein, nor the exact structure of the proteins themselves. Still, he remains optimistic.

It always seems like we’ve surpassed or learned to contain nature’s capabilities with our own man-made ones. Then one day nature reasserts herself. It could be in a violent way, like a hurricane. Or a benign way like this mollusc experiment. Everyday seems to introduce a brave new world.