These spiders launch their webs at prey. Find out how they’re so deadly accurate
Scientists have just figured out how these clever spiders know exactly when it’s time to launch themselves and their web toward prey. Scientists have just figured out how these crafty spiders know exactly when it’s time to launch themselves and their web toward prey.
Researchers at the University of Akron in Ohio conducted the study, hoping to confirm a hunch. Researchers at the University of Akron in Ohio conducted the study to confirm a hunch. The sound is their cue for striking. The findings not only shine a light on these mysterious creatures, but also suggest that sound is more important to spider hunting in general than we currently assume.
Spiders are well known for the variety of methods they use to capture prey. Some spiders are agile jumpers who pounce upon their unwitting victims. Others build traps to create an ambush. And some go fishing. These tiny arachnids are smaller than one centimeter and build webs which at first look like static orbs. They also weave a tension-line that connects the middle of the web with a nearby rock or structure. The spiders stretch the web into a cone when they are on the hunt for food. They pull the line forward while facing the opposite direction. The spider releases the line and rapidly throws the web in the direction of the prey. The slingshots spiders are different from other catapulting species in that they don’t rely on the prey touching the web for them to attack. So researchers Sarah Han and Todd Blackledge decided to look closer for themselves.
As previously observed, “slingshot spiders will release their webs in response to cues like people snapping their fingers nearby
, but no one had studied this in detail, nor their response to nearby, contactless prey,” Han, a biologist studying the mechanics of spider webs at Akron, told Gizmodo in an email. The researchers then presented the spiders with two stimuli: wing-flapping mosquitoes stuck to a thin strip of black construction paper (allowing them to move the bugs as they saw fit) and a tuning fork set to vibrate at a frequency matching the typical winged insect prey. Researchers observed that spiders rely on hearing to determine the right moment to attack. They measured spiders moving up to 50g at speeds of almost three feet per second and were attached to strips of black construction papers with wing-flapping insects. Two short video clips of the spider’s catapult trick (provided by the researchers) can be seen below or via this YouTube link.
During one experiment, for instance, the spider did nothing when a motionless mosquito was clearly in the cone’s capture zone, but it then immediately sprung once the mosquito’s wings began flapping. These spiders also responded to tuning forks, which supports the notion that sound plays a key role in their hunting. Their vision is unlikely to play a significant role either, as these spiders are facing away from the cone, and do not have the developed eyes of some spiders. Unlike people, a spider’s “hearing” doesn’t come from having ears, but from tiny specialized hairs on its legs called trichobothria.[research that co-author Blackledge had taken part in]”These spiders hold their webs in tension, like a slingshot, and will release their webs in response to the sounds of approaching flying insects, releasing webs before the insects make contact with the web,” Han explained. “Spiders preferred to release their webs when insect prey were close enough to the front of the web that they would be hit by silk upon the web’s release.”
The team’s findings were published Wednesday in the Journal of Experimental Biology.
While the researchers’ work may have solved the biggest question about the slingshot spider, there are plenty more curiosities left to untangle. Although they do not rely on prey touching their webs to determine when to attack, their bodies may still use sound transmitted by the web and through the air. This could help them to know when the target is in front of their cone. Slingshot spiders probably also aren’t the only arachnids that primarily use sound to hunt, which leaves open the possibility that sound is much more crucial a tool to spiders than currently understood by scientists.
“A broader implication of this work is that sound may be a very important and understudied factor in how spiders perceive their environment,” Han said. Recent studies have examined how spider webs detect sounds across a room. How spiders build and tension their webs could be affected by what they hear.
