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A spider woven with a triangle keeps its web in tension.
S.I. Han
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S.I. Han
A spider woven with a triangle keeps its web in tension.
S.I. Han
This high speed maneuver is a nightmare if you are a fly.
There is a type of spider that can slowly stretch its web and then release it, causing it to catapult forward and trap unsuspecting prey.
Triangular spiders-weavers use their own website in the same way that humans could use a slingshot or crossbow. Scientists at Akron University said it was a process called "power amplification" and they published their research in the report of the week from the journal Proceedings of the National Academy of Sciences.
The canvas is extensible, allowing the spider to amplify its own power using what scientists call "elastic recoil". The co-author of the study, Daniel Maksuta, a physicist at Akron University, told NPR that the maneuver "was causing much greater forces and therefore much greater acceleration".
Scientists say this slingshot-shaped movement shows that spiders can use a tool, their own website, in a way that only humans were known to do.
"I think it's just an incredible picture to think – spiders charge energy into a spiderweb and then deploy it to catch prey," says Sheila Patek, a biologist with Duke University and expert in animal movement mechanics, who did not participate in the study. Besides humans, she says, "I can not think of another example in which an animal, you know, takes something outside that it has built and then loads it" in the same way.
Here's how it works: A woven triangle spider forms a triangle-shaped web with a single thread that connects the main body of the triangle to a wall. Then, while grasping this single wire, "he walks back and tightens the band to store this elastic energy throughout the triangular shape of the band," says Sarah Han, a biologist at Akron University. and lead author of the study.
The spider coils more and more stretched one of the strands between her legs, as if she was pulling a rubber band. Han says that she has seen spiders holding this wire wrapped for hours, waiting for their prey to fall into the web.
A woven triangle spider uses its hind legs to maintain a coiled anchor line, which she has built while stretching and stretching the canvas.
S.I. Han
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S.I. Han
A woven triangle spider uses its hind legs to maintain a coiled anchor line, which she has built while stretching and stretching the canvas.
S.I. Han
"When he feels a prey hitting the canvas, he releases his paws from the back line," Han explains. "And this causes the spider and the web to move forward with this release of energy, as if you had relaxed the elastic … This causes oscillations in the web that begin to entangle the prey . "
She says that the spider can repeat this several times, tightening and releasing the web so that the prey is more and more entangled and trapped.
The web and spider gush with incredible velocity – Han says it's the equivalent of traveling about 400 spider body lengths per second.
To study how spiders did this maneuver, scientists collected near the Ohio University in Ohio and asked them to build canvases in the laboratory. They then locked the canvases in terrariums and released flies. Eventually, the fly would fall into the spider's web under the gaze of scientists.
"We recorded all this with high speed video cameras," Han said. They would then use "motion tracking and software to obtain position data, which allows us to obtain information such as speed and acceleration".
Han said that it was not the first time that anyone noticed the awesome spider maneuver, but that "no one had really quantified it" until the first time. to their study.
It should be noted that there are many types of spiders and that they use their webs in different ways. For example, orb-weaver spiders create the type of spiral circular canvases that probably come to mind when you think of what a spider's web looks like. This kind of spider does not pull its web on its prey – the web remains static.
In addition, scientists explain that when biologists think of "power amplification," they describe how animals store and release energy. in their own bodies. There are many examples, such as flea and frog jumping and the shrimp of a shrimp mantis.
But scientists say that the triangular spider-weaver had largely no need to develop methods to store and release energy in his body, just like these other animals – because she adapted her own tool, a canvas, like a weapon.
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