Metal impregnated mandibles give these ants a razor-sharp bite

Some species of ant deposit individual atoms of zinc on their teeth to make them tough, durable and sharp.  

Ants have teeth, called mandibular teeth that are actually outside of their mouths, on their clasping mandibles. They have to be sharp to compensate for their very low bite force. In order to make them sharp, some species have evolved to tip their mandibular teeth with zinc, which they sequester from their diet.

In a recent study, Robert Schofield, from the Department of Physics at the University of Oregon, and his colleagues used a process called probe tomography to look at the atomic structure of the tip of ant teeth, to determine their makeup. They found that zinc atoms bind with protein in the ant mandible. Zinc can represent up to eight per cent of the total weight of each mandibular tooth. 

Ant adult teeth 

The ant's mandibular teeth start out being very soft. The zinc comes in the first days of adulthood, which makes the teeth about three times harder, long lasting, but not brittle. Schofield says by comparison, the early teeth are about as hard as plastic, but when the zinc is added the hardness is more like that of aluminum. 

Ants don't have a set number of mandible teeth, it varies across both species and individuals. But they aren't the only ones with such teeth.  Schofield says spiders, beetles and centipedes are all very good at taking zinc from their diet and using it to make sharp teeth.

Produced and written by Mark Crawley