Ballistic high-powered spider webs overcome dangerous prey defenses

Predator-prey interactions are a major selective force shaping kinematic
performance, driving the evolution of extreme speed and power in animal
movements. Small animals such as mantis shrimps, trap-jaw ants and
slingshot spiders exhibit some of the fastest biological movements to
capture prey, utilizing latch-mediated spring actuation mechanisms that
generate power outputs several orders of magnitude greater than muscle
alone. 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.,
which is selectively triggered by the defensive behavior of a specific
prey – the green tree ant (Oecophylla smaragdina). We argue that the
extreme prey specialization of the ballista spider has driven the
evolution of exceptional snare performance.