Deep in the rainforests of northern Queensland, Australia, researchers have found a small spider with a remarkable method for catching prey. Called the ballista spider, the species builds a silk-based trap that flings ants upward into its web at accelerations of up to 140 times the force of gravity. The discovery, reported in Current Biology, shows one of the most specialized prey-capture systems known in nature. The spider targets aggressive green tree ants, using a mechanism similar to an ancient siege engine. It belongs to the genus Propostira within the cobweb spider family. Although it lacks a formal scientific name so far, its hunting approach drew quick notice from scientists. Unlike many spiders that take varied insects, this one focuses almost entirely on green tree ants, which are known for strong bites and rapid recruitment of colony members. Most predators avoid these ants due to the danger, yet the spider has developed a way to capture them without direct contact. It spends hours constructing the trap, anchoring silk to plants or the ground and creating many taut threads bundled into a cone-shaped form near the surface. Chemical signals may also draw ants to investigate. When an ant bites the cone, the stored energy releases suddenly, pulling the insect off the ground and launching it more than 30 centimeters into the web above. High-speed recordings showed accelerations reaching 1,367 meters per second squared. The spider stays in its web while the ant activates the trap itself, avoiding any direct risk. The find was first noted by a biomedical researcher and spider photographer, leading a university team to conduct ten days of field observations with infrared and high-speed cameras. The work highlights how evolution can yield precise adaptations using natural materials for mechanical advantage.
