The Power Behind an Ant’s Bite
By Busola Awobode
Any person who has ever had the misfortune of being bitten or stung by an ant, a spider, or any such arthropods would know how painful it can be. These insects can latch on fiercely and oftentimes it’s impossible to shake them off. It is almost unbelievable how such small insects can pierce and cut through various tough materials including human skin. Yet they do.
It is known that arthropods that routinely bite, pierce, or sting have slashing and piercing parts that are infused with metals such as zinc and manganese. These metals are referred to as Heavy element biomaterials (HEB) and they make the insect appendages tough and durable. However, the examination of the mandibles of the Leafcutter ant (Atta cephalotes) has given more insight into just how these appendages can work. A team of scientists lead by Robert Schofield, a biophysicist at the University of Oregon looked at the mandibles of these ants using an Atomic Force Microscope (AFM) and have found that the zinc atoms in the “teeth” of these ants are dispersed homogenously. This smooth distribution allows the edge of the ant’s teeth to form a fine point and keep them sharp for a long time.
Schofield, R.M.S., Bailey, J., Coon, J.J. et al. The homogenous alternative to biomineralization: Zn- and Mn-rich materials enable sharp organismal “tools” that reduce force requirements. Sci Rep 11, 17481 (2021). https://doi.org/10.1038/s41598-021-91795-y
These insect mandibles vary drastically from human teeth which are flatter and duller. The teeth we use have a calcium-rich exoskeleton called enamel which like zinc is durable and tough. However, if you were to examine enamel, we would see that the calcium and phosphate molecules are distributed in a chunky crystal matrix that forms around the carbon, hydrogen and oxygen atoms. So, while our teeth are strong, the pattern of distribution keeps them from being razor-sharp. Thus, we still struggle to tear through very tough materials despite the power of our jaws.
While humans use their teeth mainly for eating, arthropods use their appendages for anything from building homes and collecting food to defense. So, the composition and pattern of distribution of the ant “teeth” give these appendages the properties of a knife or a needle and allows them to reduce the amount of energy and muscle they use by 60 percent. This heavily compensates for their tiny muscles and small bodies and more importantly allows them to complete various tasks they need to survive.