Ajay Narendra, Pranav Joshi, Daniele Liprandi, G Anderson, Jonas O. Wolff
Predator–prey interactions are a major selective force shaping kinematic performance, driving the evolution of extreme speed and power in animal movements 1 . Small animals such as mantis shrimps, trap-jaw ants and slingshot spiders achieve some of the fastest biological movements to capture prey by using latch-mediated spring actuation mechanisms that produce power outputs several orders of magnitude greater than muscle alone 2 , 3 , 4 . These known power-amplified systems are actively controlled by the predator and act on non-specific prey. Here, we report a unique spring-actuated snare in the Australian ballista spider Propostira sp. that is selectively triggered by the defensive behavior of a specific prey — the green tree ant, Oecophylla smaragdina . We argue that the prey specialization of the ballista spider has driven the evolution of exceptional snare performance. Video abstract