If you're an ant, running into an antlion is as a bad as it sounds. But a team of researchers have figured out that one kind of ant, the trap-jaw ant, has a unique way of escaping the burrowing predator's clutches: The ants use their mandibles to jump to safety.
Researchers already knew that one species, the Odontomachus brunneus, had particularly powerful jaws that close at an incredible speed. The jaws catch prey, dig in the ground, help to care for larvae, and protect the ant. Researchers knew that, sometimes, the trap-jaws had been known to jump with those jaws, too, presumably in order to escape danger, study co-author Fredrick Larabee said in a statement. "But it was unknown whether this behavior was meant to help them get away from a predator, and it wasn't clear that it actually improved their odds of surviving an encounter with a predator," Larabee said.
So, does the dramatic jump help? Yes. It doubled the ants' survival rate.
Researchers placed trap-jaw ants in a sandy test-field, where an antlion was waiting. Antlions -- larvae of a dragonfly-like flying insect -- dig pits under the sand to form a conical pit of doom that's quite hard for ants to escape. Sometimes an antlion will fling sand at an ant in order to trigger a little avalanche, pushing the ant closer to its death. Here's one failed escape:
The ants who were free to jump as they pleased away from the antlion jumped to safety 15 percent of the time, "but when we glued their mandibles shut before dropping them in the pits, they couldn't jump at all. It cut in half their survival rate," Larabee said. Some ants were able to escape by running out of the pit without a jump.
Co-author Andrew Suarez described how that jumping works to National Geographic:
"They produce so much force that when they strike [a part of the ground] that's relatively immovable, that force gets projected back on the ant and they go flying through the air," says Suarez..."It's like popcorn. They go bouncing everywhere."
Researchers believe that trap-jaw ants evolved their powerful mandibles in order to catch fast prey. And they think the jumping escape might be an example of a feature that evolved for one purpose becoming useful in an entirely different way. "In this case," Larabee said, "a tool that is very good for capturing fast or dangerous prey also is good for another function, which is escape."