WEB SHOOTER WEN : NATURE ESSAY AUSTRALIA

WHAT A tangled catapult they weave. In the dead of night - a predator lays its trap in the rainforests of  Queensland, Australia. It spins silky, spring-loaded webs, appears to coat them with tantalizing, and yet enraging scent, and then waits.

Its prey comes along. The victim rushes that way, becomes aggressive and bites the offending way. The trap snaps, and the prey catapults through the air - right to where its hunter awaits.

THIS hunter is a newly discovered spider, and the scientists for now are calling it the ballista spider, after a crossbowlike weapon from ancient Rome. Its prey is an ant. And the unusual springy snare?

It maybe the first known example of a spider's setting a trap whose mechanism is triggered by the prey itself, as described in a study from the journal Current Biology.

The discovery process began several years ago, when Gregory Anderson, an author of the study, happened upon the spider's cone-shaped webs. He shared the find with a group of researchers, who thought it need an investigation, according to Ajay Narendra, a sensory biologist in Australia who was part of that group.

The team trekked into the rainforests of Cape York Peninsula in Australia to watch the spiders with cameras and infrared lights and to collect samples of the springy silk. In total, they recorded five of the fast moving traps on films.

'' We spent several nights watching the filming these spiders build their webs and hunt green ants," Dr. Narendra said.

'' We had to film at 5,000 frames per second to visualize, '' the hunting strategy, he added, [ After calculations, he found the trap launched ants faster than 1,300 meters - 4,300 feet - per second squared]

They observed several other things too : The spiders were hunting one specific ant, the green tree ant, which is highly territorial and aggressive. The spiders closely mimicked the ant's appearance, with a large green abdomen and segmented body.

And the spiders seeming to be using the ant's aggression against itself. Researchers think they might be coating their web traps with pheromones that attracted the ant and elicited its aggressive biting response.

The biting is what sets off the trap and launches the victim into the air toward the ballista spider.

!WOW! thanks K.R. Callaway.