Image Credit: Nathan Burkett-Cadena via Wikimedia Commons // CC BY-SA 3.0

Trap-jaw ants give a whole new meaning to the term “Jaws of Life.” The carnivorous ant’s snapping jaws feature one of the fastest animal reflexes in the world [PDF], and they don’t just use them to take down prey. Their super-fast mandibles are also an escape mechanism, as entomologists from the University of Illinois, Urbana-Champaign describe in a new study in the journal PLOS ONE.

The researchers studied the tactics trap-jaw ants use to try to escape pit traps dug into sand by antlion larvae, which hide in wait at the bottom of the pit for unlucky ants to lose their footing. The sides of the sand pits are unstable, so the harder the ant struggles to get out, the more likely it is to fall in. The antlion larvae then pull their prey into their hole, inject it with intestinal fluid, and devour it. 

Some trap-jaw ants were able to escape this gruesome fate by snapping their mandibles against the sand on the side or bottom of the pit, exploding them out of danger. Trap-jaw ants can shut their jaws at speeds of up to 134 mph with a force up to 300 times their body weight. This evolutionary mechanism comes in handy when attacking fast or poisonous prey, but it seems to also have been co-opted as a defense strategy.

While most of the time they simply ran away, Odontomachus brunneus (native to Central and South America) hurled itself away from potential predators with its spring-loaded jaws in about 15 percent of interactions observed between the ants and antlionsNot every attempt to bite a way out of the pit succeeded: only about a quarter of the jaw strikes generated enough power to allow the ant to jump. However, when ants had their mandibles glued together, they were significantly less likely to escape from the pit.