Packet hunter spiders are found in places other than your nightmares. While most spiders enjoy a solitary life, 20 of the approximately 50,000 known spider species live in colonies. one kind, Anelosimus It lives in very large colonies of up to 1,000 individual spiders that work together to build webs that span several meters. When they fall prey to their web, this social network paw-paw They coordinate and attack their victims together, allowing them to take down prey much larger than if they hunted alone. Until now, the way these spiders carried out such coordinated attacks was still a mystery.
The study found that spiders use the vibrations in their large webs to choreograph the choreography of a synchronized swarming process.
“The remarkable thing is that there is no leadership role among these spiders,” said Raphael Janson, a researcher at the Research Center for Animal Cognition (CRCA) at the University of Toulouse in France and senior author of a new study on social spiders. . . Instead, the entire spider colony coordinates its attacks with each individual receiving the same information.
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When attacking a colony, the spider descends on its prey by harmonizing two phases of movement: approaching the struggling victim and standing still. This allows the spiders to time their approach so that they each attack at once.
Using field observations and computer simulations of this coordinated attack, Jenson’s team learned that the attack was directed almost entirely by vibrations on the shared web.
“When prey falls into the web, it causes the spider to move,” Jenson told Live Science. “But after a while, they all stopped for a few milliseconds before they started moving again.”
By luring spiders with dead flies attached to the ends of the vibration generators, the researchers demonstrated that hunting behavior is actually the result of a defenseless prey struggle. However, this does not explain the coordinated movement of the colony.
For this, scientists need computer models. The model revealed that while the prey’s vibration might trigger the initial movement, it was the vibration caused by the spider colony that allowed the predators to coordinate their attacks. When each spider feels a vibration from its prey, they start walking. But the steps of hundreds of spiders encountering struggling insects also send vibrations through the fibers of the web, the muffled sound of trapped food.
“It’s like when you’re in a room with people talking,” Jenson said. For spiders, every step you take makes a sound. Then they have to stop moving so they can listen to their prey, to make sure they are still walking in the right direction.
The quieter the struggling prey, the more difficult it is for the spider to coordinate stop-and-go movements. When the researchers vibrated the web and then released the bait, the colony responded by moving toward the prey, but then each spider had to stop moving to “listen for” signs of confusion. The scientists found that if the prey vibrated violently, the colony did not need to be quiet, resulting in a lack of synchrony.
The study was published March 7 in the journal Prosiding National Academy of Sciences.
Originally published in Live Science.
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