Metallic edges make ant teeth razor sharp

The average ant tooth is thinner than a human hair and able to slice through tough leaves and even flesh without breaking. Researchers now know how: the edges of ant teeth are lined with a layer of uniformly distributed zinc atoms, enabling ants to use at least 60% less force than if their teeth were made of a material similar to human teeth (Sci. Rep. 2021, DOI: 10.1038/s41598-021-91795-y). Biophysicist and lead author Robert Schofield of the University of Oregon had spent decades measuring the miniature-scale mechanics of the cutting, piercing, and stinging tools of crawly critters, but the actual makeup of structures like ant teeth were too small to see, even with electron microscopy. Schofield teamed up with materials scientist Arun Devaraj from Pacific Northwest National Laboratory to image the tips of ant teeth using atom probe tomography. Biomineralized human teeth or crab claws are hard, but because they are formed with nodules of interspersed minerals, they are susceptible to fracture. In contrast, ant teeth are composed of protein that binds individual atoms of zinc to form a sharp, precise edge that evenly distributes mechanical load. “Even for these miniature tools, the nanoscale distribution of these elements is completely changing its properties,” Devaraj says.