Pack hunting spiders exist in places other than your nightmares. While most spiders enjoy solitary lives, 20 of the roughly 50,000 known spider species live in colonies. One species, Anelosimus eximius, lives in huge colonies of up to 1,000 individual spiders that work together to build several-meter webs.
When Prey falls into their web, these social spiders coordinate and attack their victim together, which allows them to take down much larger than they could if they hunted alone. Until now how these spiders carry out such coordinated attacks. The spiders use vibrations in their mega-webs to choreograph a synchronized swarming process.
As the colony attacks, the spiders descend on their Prey by synchronizing two-movement stages: closing in on their struggling victim and standing still. This allows the spiders to time their approach so that all of them strike at once. They are using both field observations, and computer simulations of this coordinated attack, Jeanson’s team learned that the attack is directed almost entirely by vibrations in the shared web.By luring the spiders with a dead fly glued to the end of a vibration generator, the researchers showed that hunting behavior was triggered by the struggling of helpless Prey.
However, that didn’t explain the colony’s coordinated movements. Scientists needed a computer model. The models revealed that while the Prey vibrations might trigger the initial movement, the vibrations made by the spider colony enabled the predators to coordinate their attack.As each spider sensed vibrations from the Prey, they started walking. But the steps of hundreds of spiders converging on a struggling insect also sent vibrations through the web’s fibers and muddied the sounds of a trapped meal.