For one tiny Australian spider that lives in Australia, it is mystifying that the secret to taking down ants twice its weight is somersaulting.
Ants — armed with powerful jaws and sometimes chemical weapons — are so dangerous to spiders that fewer than 1 percent of arachnids attempt to hunt the insects (SN: 9/8/21). High-speed footage has revealed that the Australian Ant-Slayer Spider (Euryopis umbilicataThis is a risky prey that can be tackled by jumping over and lassoing the victims with silk.
The hunting maneuver hasn’t been found in any other spider speciesResearchers report September 19th in the Proceedings of National Academy of Sciences.
“This acrobatic behavior is just fascinating. I’ve personally never seen this kind of hunting,” says Paula Cushing, an evolutionary biologist and curator of invertebrate zoology at the Denver Museum of Nature & Science, who was not involved in the study.
Alfonso Aceves Aparicio is a behavioral ecologist at the Max Plank Institute for Chemical Ecology (Jena, Germany). He stumbled upon the somersaulting snakes while walking home that night. Aceves Aparicio was a Macquarie University graduate at the time. He was intrigued to see the dark dots strewn across the paler bark of an eucalyptus.
The dots represented tiny spiders among ants. The spider leapt suddenly. “I thought it was trying to escape an ant,” Aceves-Aparicio recalls. “But then I saw the ant floating and I thought, woah, there’s something going on here.”
Aceves Aparicio borrowed high-speed cameras to get a better view of what the spiders were doing. He and his colleagues were able to see that the spiders were actually hunting ants in an entirely new way by slowing down the action.
To minimize risk, most ant-hunting spiders use nets or sneak up behind their prey to avoid danger. But despite being smaller than their prey, Aceves-Aparicio’s spiders were facing banded sugar ants (Camponotus consobrinus) Face forward. Each spider set itself up so it could observe the ants climbing up the tree. Each time an ant approached, the spider would flip above it. Once it was up, the spider snatched a thread from silk onto the ant.
This single tethering action — performed in the space of milliseconds — determined whether the hunt would succeed. If the tether was successful, the spider darted around the insect, wrapping it with more silk, and then pulling them away to be eaten.
What stands out to Aceves-Aparicio and his colleagues was the technique’s effectiveness. Predators such as lions and wolverines tend to miss approximately 50 percent of their targets. 85 percent was the success rate for the 60 spider hunts that researchers captured.
Aceves-Aparicio believes that extraordinary behavior can be hidden in plain sight. “The message here is to have a little curiosity and to pay attention,” he says. “There are things going on everywhere. We just have to be there to find them.”
