A recent finding in Australia’s tropical rainforests has astonished scientists with a spider species that uses a spring-loaded silk trap to launch prey through the air. Dubbed the “ballista spider,” the arachnid builds a cone-shaped snare to catapult green tree ants into its web. The discovery, detailed in a study published in Current Biology, was described by biologist Ajay Narendra from Macquarie University as “breathtaking.”
The spider, belonging to the Propostira genus, is yet to be formally named. Researcher Greg Anderson first observed the spider in 2022 in a remote rainforest on Queensland’s Cape York Peninsula, where a green tree ant was seen flying through the air and getting trapped in its web. This observation led a team from Macquarie University to investigate further in 2023.
Using high-speed cameras, the researchers documented the spiders’ hunting strategy over 10 days. The spiders, which are nocturnal and measure three to five millimeters in length, spend their days hidden under leaves and construct elaborate traps at night. These traps involve silk tension lines attached to an anchor point, forming a cone-shaped structure that launches the trapped ant into the air, landing it in the spider’s main web.
The green tree ants are attracted to the trap within minutes of the final silk layer being placed, suggesting the use of pheromones to lure this specific type of ant. Ajay Narendra suspects this evolutionary approach allows the spiders to hunt the formidable green tree ants without direct confrontation. The team plans to study the spider silk further to determine the presence of pheromones used in prey specialization.
Saad Bhamla, an associate professor at the University of Colorado-Boulder’s BioFrontiers Institute, suggests a simpler explanation for how the spiders target their prey, speculating that the ants’ aggressive behavior might play a role. The ballista spider’s launching mechanism subjects the ants to high G-forces, surpassing those experienced by jet pilots, making it a unique predator in the arachnid world.
The hunting tactic of the ballista spider differs from that of the slingshot spider, another species utilizing a similar technique. While the slingshot spider actively launches itself at flying insects, the ballista spider stores energy in its silk trap to launch prey with remarkable force while maintaining a safe distance. The discovery underscores the ongoing mysteries and wonders of nature, with more revelations awaiting in the natural world.