A newfound spider species discovered in the tropical rainforests of Australia has amazed scientists with a unique hunting method that propels prey into the air using a silk trap loaded with a spring mechanism.
The findings, detailed in a recent publication in the journal Current Biology, reveal how this small arachnid constructs a cone-shaped snare to fling green tree ants into its web, earning it the moniker “ballista spider” in reference to ancient Roman siege weaponry.
Biologist Ajay Narendra, a key researcher from Macquarie University in Australia, expressed awe at witnessing the spider’s behavior, which belongs to the Propostira genus and is yet to be formally named.
The spider was first observed by researcher Greg Anderson in 2022 when a green tree ant was unexpectedly launched through the air and caught in a web in a remote rainforest on Queensland’s Cape York Peninsula. This discovery led the team to travel to northern Queensland in 2023 to investigate further.
Using high-speed cameras, the researchers spent 10 days documenting the spiders’ unconventional hunting strategy. The spiders, measuring three to five millimeters in length, are nocturnal creatures that hide under leaves during the day and emerge at night to build intricate traps.
By setting up silk tension lines in a cone-shaped structure, the spiders ensnare green tree ants that trigger the trap. As the ant struggles, the tension is released, propelling the insect about 30 centimeters into the air and directly into the waiting predator’s web.
The research team observed that the green tree ants were attracted to the trap within a minute of the final silk layer being placed, indicating the potential use of pheromones to lure these specific ants.
Narendra believes that this passive hunting approach may have evolved as a strategy to capture green tree ants, known for their collective strength, without engaging directly with them. Further investigations are planned to analyze the spider silk and identify any pheromones involved in prey targeting.
The remarkable launch mechanism of the ballista spider subjects the ants to significant G-forces and surpasses the force generated by the slingshot spider, another species utilizing a similar hunting technique. Unlike the slingshot spider, the ballista spider stores energy in its silk trap, enabling it to launch prey with substantial force while maintaining a safe distance.
Saad Bhamla, an associate professor at the University of Colorado-Boulder’s BioFrontiers Institute, suggests that the spider’s prey targeting could be influenced by the aggressive nature of green tree ants. Bhamla’s research on slingshot spiders highlights differences in hunting strategies, emphasizing the unique capabilities of the ballista spider.
The ongoing exploration of nature continues to unveil fascinating discoveries, showcasing the complexity and ingenuity of natural ecosystems.
