Ballista Spider Uses 140g Web Catapult to Snare Green Tree Ants

3 articles · Updated · The Conversation · Jun 22

Researchers in Queensland’s Cape York Peninsula identified a Propostira “ballista spider” that builds a spring-loaded silk snare triggered specifically by green tree ants.
A worker ant bites the cone-shaped lure, detaching it and firing the ant into the core web at up to 1,367 meters per second squared—about 140 times gravity.
The thin outer silk appears to provoke the ants, possibly through pheromones, while the spider waits until the prey is fully tangled before moving in to wrap and eat it.
Gram for gram, the web stores 78.17 kilojoules per kilogram and briefly delivers 11.73 megawatts, which researchers say exceeds any known biological catapult.
The finding, published in Current Biology, highlights extreme prey specialization: the prey triggers the trap itself, likely helping the spider yank ants away before nestmates can respond.