130G: An Australian Spider’s Trap Catapults Prey at Dizzying Speeds

Researchers have recently had the opportunity to dissect the remarkably sophisticated hunting strategy of an Australian spider. Involving natural catapults, it enables it to effectively capture ants.

A Formidable Strategy

Renowned for its name echoing those famous ancient siege engines capable of launching projectiles for hundreds of meters, this “ballist spider” spends most of its days beneath the forest litter. At dusk, it begins to tension its elastic trap. Consisting of dozens of interwoven strands fixed to a leaf, it forms a largely conical structure.

After several hours of work, it is finally ready. Its crafter will then apply to the surface of the leaf an odorous and sticky chemical substance, which has the peculiarity of attracting only the green arboreal ants (Oecophylla smaragdina).

Upon contact, the mandibles of these ants become clogged, and their spry movements to free themselves end up pulling the trap’s anchorage, which breaks and flings them about thirty centimeters off the ground, straight onto the spider’s main web. It is assumed that these devices are stretched at a reasonable distance from ant colonies in order to lure isolated individuals and thus reduce the risk of a mass retaliation.

“Building such traps for every meal may seem like a Herculean task, but these ants constitute an especially reliable food resource,” write the authors of the new study, published in the journal Current Biology.

Lightning Launch

Belonging to the genus Propostira, the species at the heart of these studies thrives in the tropical forests of Queensland, in northeastern Australia. In early 2023, Narendra and Pranav Joshi, from Macquarie University, spent about ten days examining its nocturnal routine.

Analysis of footage captured by ultra-high-speed cameras (ranging from 5,000 to 7,000 frames per second) revealed that when the trap was triggered, its future meals underwent an acceleration of 130 G, i.e., 130 times Earth’s gravity.

“This corresponds to roughly 1,367 meters per second squared,” explain the researchers.

These are not the only intriguing strategies employed by spiders. Some spit on their prey until death ensues, while others build “giant scarecrows” to mislead their predators.