Australia's tropical rainforests have yielded a remarkable new species of spider, one that has evolved an extraordinary 'catapult' trap to capture aggressive green tree ants. The nocturnal predator, yet to be formally named but dubbed 'ballista', is found in the remote northern Queensland region.
The research team from Macquarie University, led by Professor Ajay Narendra, has made a groundbreaking discovery: the ballista spider constructs a complex snare of tension lines that can fling unsuspecting ants into a larger web with forces equivalent to 15 times the g-forces experienced by jet pilots. This sophisticated hunting method allows the tiny spider to 'pick off' individual ants and transport them away from their colonies, avoiding the risks posed by their chemical defences and rapid recruitment capabilities.
The study, published in Current Biology, reveals that the ballista spider inhabits trees home to Oecophylla smaragdina – aggressive green tree ants. During the day, it remains hidden beneath leaves in webs. At night, it descends to a lower surface, creating an anchor point with silk before meticulously constructing a cone-shaped 'scaffold' of dozens of tension lines.
When green ants approach and bite the trap, the snare springs into action, launching the prey into the spider's web with extreme acceleration. Notably, only green ants are captured, even when other nocturnal ants are introduced near the trap – a finding that suggests the spider incorporates pheromones to specifically lure and agitate its preferred prey.
This innovative hunting strategy is unprecedented, with Professor Narendra describing it as the 'only known instance where a spider's web is designed to catch a single prey species'. The discovery was made by biomedical researcher and spider photographer Greg Anderson, who initially observed this unique behaviour. As peer-reviewed research, it adds to our understanding of the remarkable adaptations within the natural world.