Watch this new spider species launch ants right into its web

There’s no easy way to catch a green tree ant. These aggressive arthropods have a powerful bite and can spray acid into the wound. It’s no wonder that few predators dare to hunt them, but scientists just discovered a spider brave enough to do it. 

In fact, this newly discovered species, which scientists are calling the ballista spider, hunts green tree ants exclusively and does so by setting sophisticated spring-loaded snares that launch the ants into their webs at extreme speeds, a trapping system seen in spiders for the first time. 

The discovery of this undescribed but likely new species of spider was announced in a new study in the journal Current Biology. 

Spider serendipity

In 2023, Greg Anderson, a biomedical researcher and spider taxonomist, was looking for spiders in the rainforests of Australia’s Cape York Peninsula when he came across something that made him do a double take: a spider that appeared to be setting a trap.

The tiny, earth-toned spider, no bigger than a penny, descended from its web onto a leaf below and began attaching a silk thread to it. The spider repeated this process, reinforcing its silk until tension had built between its web and the leaf. 

Eventually, the spider returned to its web and waited. Not long after, a green tree ant walked onto the leaf and, after taking one close look at the strand, started biting it.

In a flash, the strand was severed, and the ant was catapulted directly into the spider’s web. As the ant struggled, it became more entangled—and eventually became a tasty snack for the spider.  

Super speed

Everything happened so fast that Anderson could barely make out what had occurred. So, a few years later, he returned to learn more. But this time Ajay Narendra, an entomologist from Macquarie University in Australia, joined him. Once they located the spiders, the researchers set up high-speed cameras around their webs and waited for nightfall, which is when these spiders hunt. 

On high-speed cameras, the dramatic scene played out in a flash—but scientists were able to study them in freeze motion. “The ant was literally there in one frame and gone in the next,” says Narendra. “We realized that [the trap] is exceptionally, exceptionally fast, something we have never ever seen before.” 

While spiders have been known to get creative when catching prey—such as net-casting spiders, who throw small silk nets on their prey to entangle them, or slingshot spiders who use their conical webs like catapults, launching both themselves and their sticky web towards their prey—scientists had never observed a spider using a premade trap to launch prey to their doom.

After analyzing the footage, the scientists determined that gram for gram, the snares stored more energy and exerted more power than any known biological catapult. 

According to their calculations, a kilogram of the silky snare would contain enough kinetic energy to unleash nearly 12 megawatts of power when triggered—the equivalent of enough energy to power thousands of homes for a moment.

The snares launched the unsuspecting ants at speeds up to 1,367 meters per second, which is roughly one-and-a-half times as fast as a bullet fired from a rifle. 

Picky eaters 

But it wasn’t just the speed of the spider’s snare that surprised scientists; it was how specialized each snare was. In every video, green tree ants were the only insects who paid any attention to the snare’s trigger and the only species falling victim to the spiders. 

“It’s very, very rare in the animal kingdom for predators to hunt only one species of prey,” says Narendra. 

Green tree ants live in large colonies on the Australian coast, and the study’s authors believe the spiders evolved this unique trapping behavior to capitalize on their abundance. But how the spiders lure these ants to trigger their traps remains a mystery. However, the researchers have a theory. 

“We think that the spider is adding some pheromones or chemicals to the snares that only attracts the green tree ants and no other species,” says Narendra. “Which is absolutely mind-blowing.”

Few other spiders do this. And whatever the ballista spiders are adding to the triggers of their traps seems designed to infuriate the ants, causing them to attack the silk strand and ultimately cut it. The researchers say they plan on studying the chemical compounds on the snares to test their hypothesis. They also plan on formally naming the species and figuring out where it sits on the tree of life.

In the meantime, Narendra hopes that the discovery of this incredible spider will inspire more people to “go out and watch animals in the wild.” 

If more people did that, more such discoveries would surely be made, says Sarah Crews, an entomologist at the California Academy of Sciences, who was not involved with the study.  

“It took somebody just going out and actually looking at it and recording it,” she says. While Crews says lab work is no doubt valuable, she encourages more scientists to get out into the field and just explore. She says this spider and its astounding trapping ability was probably “right there in front of everybody for a long time.”