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Electric Fields Used By Spiders To Take Flight: Research

Charles Darwin remarked on the behavior when tiny spiders landed on the HMS Beagle, trailing lines of silk.

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A spider sits in her web. Researchers from England think spiders might be sensing and using electrostatic fields to become airborne.
A spider sits in her web. Researchers from England think spiders might be sensing and using electrostatic fields to become airborne. VOA

Since the 1800s, scientists have marveled at how spiders can take flight using their webbing. Charles Darwin remarked on the behavior when tiny spiders landed on the HMS Beagle, trailing lines of silk. He thought the arachnids might be using heat-generated updrafts to take to the sky, but new research shows a totally different cause may be at play.

Erica Morley and Daniel Robert from the University of Bristol in England were interested in exploring a second explanation for the spiders’ ability. They thought spiders might sense and use electrostatic fields in the air.

“There have been several studies looking at how air movement and wind can get spiders airborne, but the electrostatic hypothesis was never tested,” Morley told VOA.

Some observers suggested electrostatic fields might be the reason the multiple draglines some spiders use to float don’t get tangled with each other. Biologist Kimberley Sheldon from the University of Tennessee at Knoxville, who was not involved in the new research, pointed out that “though these spiders will have five or six draglines, those strands of silk do not get entangled. So we’ve known for a while that electrostatics probably [are] at least interacting with the spider, with the silk lines themselves, to keep them from getting tangled.”

Morley and Robert created a box with a grounded metal plate on the bottom and a plate on the top that they could pass an electrical current through. The scientists placed spiders in the box and turned on the voltage, watching as the creatures reacted to the electric field.

Reaction to current

When the electric field was on, the spiders lifted their abdomens into the air and started tiptoeing by raising up on the very ends of their legs. Morley told VOA that spiders only tiptoe right before they release silk draglines to fly away, in a process called ballooning.

And when the spiders did balloon and rise into the air, turning off the electric current caused them to drop.

Sheldon compared it to taking a balloon and rubbing it against your clothing. “If you hold the balloon [near your head], your hair stands on end. That’s kind of what’s happening with the spider silk.”

Spiders Use Electric Fields to Take Flight: Research
Spiders Use Electric Fields to Take Flight: Research. Pixabay

Clearly the spiders were able to sense the local electrostatic field and respond appropriately by releasing silk, but Morley and Robert wanted to know how.

“As a sensory biologist, I was keen to understand what sensory system they might use to detect electric fields,” said Morley. “We know that they have very sensitive hairs that are displaced by air movements or even sound. So I thought that it’s possible that they might be using these same hairs to detect electric fields.”

This was exactly what she observed. The small hairs along the spiders’ legs react not only to physical experiences like a breeze but also to the electric field. In nature, it makes sense for spiders to sense both the electrostatic field around them as well as wind conditions. Spiders probably use both when taking off and navigating the skies.

Mathematician Longhua Zhao from Case Western Reserve University in Cleveland has made computer models of how spiders balloon. She told VOA, “I think that both the electrical field and the fluid mechanics [of air flow] are important. They definitely play very important roles. However, we don’t know at this point which is the dominant factor.”

Also read: Did You Hear about the New Species of Spiders Named After Leonardo DiCaprio, Bernie Sanders and Barrack Obama?

Lead researcher Morley pointed out that spiders aren’t the only invertebrates to balloon. “Caterpillars and spider mites, which are arachnids but not spiders, balloon as well.” Morley hopes to see others follow up her research to see if these other animals respond in a way similar to the spiders. (VOA)

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What Lies Beneath These Invisible Footprints? Find it out Here

Researchers discover the invisible footprints hiding since the end of the last ice age

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Footprints
Researchers have discovered the invisible footprints hiding since the end of the last ice age. Pixabay

Using a special type of radar, researchers have discovered the invisible footprints hiding since the end of the last ice age — and what lies beneath them.

The fossilised footprints reveal a wealth of information about how humans and animals moved and interacted with each other 12,000 years ago, according to the study published in the journal Scientific Reports.

“We never thought to look under footprints, but it turns out that the sediment itself has a memory that records the effects of the animal’s weight and momentum in a beautiful way,” said study lead author Thomas Urban from Cornell University in the US.

“It gives us a way to understand the biomechanics of extinct fauna that we never had before,” Urban said.

The researchers examined the footprints of humans, mammoths and giant sloths in the White Sands National Monument in New Mexico.

Invisible footprints
The fossilised footprints reveal a wealth of information about how humans and animals moved and interacted with each other 12,000 years ago. Pixabay

Using ground-penetrating radar (GPR), they were able to resolve 96 per cent of the human tracks in the area under investigation, as well as all of the larger vertebrate tracks.

“But there are bigger implications than just this case study,” Urban said.

“The technique could possibly be applied to many other fossilised footprint sites around the world, potentially including those of dinosaurs. We have already successfully tested the method more broadly at multiple locations within White Sands,” Urban added.

“While these ‘ghost’ footprints can become invisible for a short time after rain and when conditions are just right, now, using geophysics methods, they can be recorded, traced and investigated in 3D to reveal Pleistocene animal and human interactions, history and mechanics in genuinely exciting new ways,” said study co-author Sturt Manning.

Also Read- Risk Of Low BMD Among Women With Less Sleep

GPR is a nondestructive method that allows researchers to access hidden information without the need for excavation.

The sensor – a kind of antenna – is dragged over the surface, sending a radio wave into the ground. The signal that bounces back gives a picture of what’s under the surface. (IANS)