The Ant That Blasts Itself Out of Danger With Its Face

"Gee ya know what Carnivorous Antlion I'd love to stay and chat but I think I left the oven on."

For ants, it’s not all invading picnics and eating my ice cream and stinging me for good measure. Sure, they live a pretty charmed life—their protective exoskeletons and tendency to hang out together have allowed them to take over the world. But a whole lot of predators have their eyes on them, so ants have to put up a solid defense, too. They can rely on those aforementioned stings, of course, while others like to get more creative with it, like one variety that fends off attackers by squeezing itself until it explodes, coating the villain in toxins.

Then there are the trap-jaw ants of the genus Odontomachus, which prefer—oh, I don’t know—not blowing themselves to pieces. As their name would suggest, these ants have remarkable mandibles, huge things that cock back and fire off at up to 145 miles per hour. The strike lasts a mere .13 milliseconds and generates so much force that an attacker can find itself tumbling through the air end over end as the ant makes its retreat. And if it finds itself outmatched, the ant will point its face at the ground and blast itself out of danger.

Here’s how those jaws work. The ant uses muscles to pull back the mandibles until a latch snaps into place, locking the jaws at 180 degrees. “And then [the ants] turn on closer muscles really intensely,” says biologist Sheila Patek of Duke University, “but the jaws don’t close because there are these little latch mechanisms that are blocking them.” When the ant wants to fire the jaws, it triggers muscles that pull out the latches, releasing a tremendous amount of stored energy.

The ant can set off the whole mess manually—say, to bite the ground to fire itself off—or automatically. Lining the insides of the mandibles are sensory hairs, so all the ant has to do is bump into its prey for the jaws to snap shut. Interestingly, these hairs are wired right to the jaw muscles, so the signal doesn’t have to waste time traveling to the brain for processing. It may seem like overkill, but when the ant is hunting blazingly fast insects like springtails, every teeny-tiny fraction of a second counts. It’s so quick that should a toad set its eyes on a trap-jaw and fire its tongue, the ant can launch itself clear out of danger before the tongue can fully unravel out of the toad’s face.

The weapon of choice. Though I suppose the ant doesn’t have a choice in the matter since the things are attached to its face.

I’d like to say that they’re actually aiming themselves when they do this, but sadly that isn’t strictly speaking … true. “It turns out that they exert very little control over their trajectory, so they are for the most part bound to flying backward at whatever angle of whatever it is they’re hitting,” says Patek. “So it’s an interesting behavior, because it really is something between an intentional act and a blooper. They don’t have a lot of control over it, but it does get them out of the way.”

It all gets even more impressive when you disturb a whole nest of trap-jaw ants. “There’s also this thing we call the popcorn effect,” says Patek, “where you walk into a nest of these things or they’re concerned about a predator and they all start popping like this all over the place and some of them land on you and sting you.”

“It’s almost like a group terror signal,” she adds, “to launch themselves all over the place and onto the predator. And they do have really bad stingers, just like wasps and bees.”

The antlion sees the trap-jaw ant’s mandibles and raises it a million dollars’ worth of horror.

Anything With ‘Lion’ in Its Name Is Probably Trouble (Except Cecil the Lion—He Was Legit)

Nowhere are the trap-jaw’s battles more dramatic than in Florida (hell, what isn’t more dramatic in Florida?), where ferocious antlions lie in wait. These predators—actually the larval form of an order called nerve-winged insects—dig pits in sand and wait at the bottom for prey like ants to tumble in. As the victim struggles to drag itself out, the antlion flicks sand at it, ideally knocking it down and into some gnarly jaws.

Scientists have figured for a century that trap-jaw ants launch themselves to escape predation, but no one had confirmed experimentally that this actually worked well enough to boost their chances of survival—until entomologist Fred Larabee of the University of Illinois, Urbana-Champaign and his colleagues came along. They got themselves some antlions, starved them a bit, and dropped in two groups of trap-jaw ants, one of normal individuals and the other of ants whose jaws the scientists glued shut.

And sure enough, unrestrained ants were twice as likely to escape a less than pleasant death as their counterparts. So “it actually does what prior to this we were waving our hands saying it does. It acts as an adaptive behavior for escape from predators,” says Larabee. What’s really interesting here is that evolution likely first produced such powerful jaws to aid the ant in hunting, according to Larabee, allowing it to punt and stun potentially dangerous prey, but it seems it was later co-opted as a defensive mechanism.

A trap-jaw ant escapes an antlion. Notice the antlion flick sand at the ant to trip it up, as if to say, “You fool. Ants don’t have ovens.”

But why evolve such wild power in the first place? A clue might be that unlike species such as the army ants, which march through the forest en masse in search of food, trap-jaws are generally solitary foragers—lone guns, if you will—with smaller colonies. Without the support of its comrades, an ant would do well to both quickly disable prey that may itself come packing a sting, and to defend itself against its enemies.

And defend itself it must: It’s an invaluable asset in a small colony. “Individual workers are more valuable because an individual worker does more in terms of foraging and comprises a larger fraction of the whole colony as opposed to, say, an enormous colony of leaf-cutter ants,” says Larabee. “So having a behavior that improves that individual forager’s survival might be disproportionately beneficial to trap-jaw ants.”

Read more at Wired Science