Australian spider catapults green tree ant with silk trap

Scientists have discovered a new spider in the rainforests of northern Australia that uses a spring-loaded silk trap to catapult a specific type of ant into its web, a hunting strategy never before documented. The spider, nicknamed the "ballista spider," belongs to the genus Propostira and measures about five millimeters long.

The discovery, detailed in a study published in the journal Current Biology, reveals an extreme example of ecological specialization. The spider hunts exclusively the aggressive green tree ant, Oecophylla smaragdina, a notoriously dangerous prey that can bite, spray formic acid, and summon large numbers of nestmates.

Researchers from Macquarie University in Australia and the University of Greifswald in Germany spent ten nights observing the spiders in rainforest near Cooktown, Queensland. They documented that the nocturnal spider spends its day hidden beneath leaves above ant trails. After dusk, it descends about 50 centimeters to a leaf, branch, or the forest floor to begin constructing its trap.

The construction process takes up to four hours. The spider creates an anchor point and then builds a cone-shaped scaffold of 15 to 60 tightly bundled silk...