Spiders fly by Electrostatic Force

[Sea Skimmer]

Pretty cool and sure helps explain how they get so far and high.

https://www.npr.org/2018/07/05/62612369 ... -literally
When Spiders Go Airborne, It's Electric — Literally

July 5, 201812:05 PM ET

Nell Greenfieldboyce

Spiders can fly long distances by releasing long strands of silk, which get picked up by the wind.
Michael Hutchinson/Cell Press

Many spiders fly long distances by riding "balloons" of silk, and a new study suggests that they're propelled by more than just the wind.

Electric fields at strengths found in nature can also trigger the spiders' ballooning behavior. And electrostatic forces can lift up the spiders even when the air is still, according to a newly published report in the journal Current Biology.

Ballooning spiders have long fascinated scientists because they fly high — they've been found more than 2 miles up — and far. These spiders land on ships in the middle of the ocean, and they're often the first colonizers of new volcanic islands, says Erica Morley of the University of Bristol.

"Although they don't have wings, they're actually pretty good at flying," says Morley. She explains that a spider will go to a high branch on a tree or to the top of a tall blade of grass and stand on tiptoe with its abdomen pointing up. It then releases long strands of silk and becomes airborne.

Curiously, Morley says, spiders balloon only when the winds are very low, like a light breeze. And some larger spiders manage to get up in the air even when it seems like there's not enough wind to make that happen. Scientists also wonder what triggers mass ballooning events — when thousands of spiders suddenly take to the air.

All of those are hints that spiders rely on something more than just the wind. What's more, ballooning silk is made of lots of strands that are released at the same time, "and these sort of splay out, as though there's a repulsive force present," Morley says.

The idea that atmospheric electric fields might affect flying spiders has been around since the 1800s, but until now, there's been no evidence that spiders could detect or use them. Morley and her colleague Daniel Robert got interested in this after reading a recent paper that showed electrostatic spider flight was theoretically possible.

"There wasn't actually any empirical data to support or dispel this hypothesis so that's what we tackled," Morley notes.

They rigged up a box with two metal plates, one on the top and one on the bottom. The top plate was connected to a voltage, and the bottom one was electrically grounded. "So between the two plates was an electric field," says Morley. "And the spiders were then put in this electric field, and we could switch it on and off and look at changes in their behavior."

The spiders reacted when the electric field was switched on.

"They try to balloon. They perform this tiptoeing behavior, and try to balloon," Morley says. "I was delighted when I saw them responding. It's very surprising. It needs a lot more investigation."

Some spiders even became airborne in the lab. "And you can change their altitude by switching the electric field on and off," Morley adds. "If they manage to become airborne, and you switch the electric field off, they will then slowly fall. And then you can switch it back on again and they will rise. So you can see that this electric field is providing enough force to lift them against gravity."

She says there's a lot more work that needs to be done to see how this plays out in a natural environment, and how this relates to their use of wind. "Wherever there's an electric field in the spider's natural environment," she says, "there is also likely to be some air movement."

[Sky Captain]

Interesting, I wonder could this effect be useful for a small drone.

[Eulogy]

Does this means that Spiderman has electric powers?

[Tribble]

Does this means that Spiderman has electric powers?

Isnt that how he sticks to walls?

[cadbrowser]

So, I'm curious then.

Is the material that makes up the strands of web have a charge of its own in order to utilize an electrostatic field for, well...basically anti-gravity?

I know that isn't the right word...but it was fun to say. So sue me.

[LaCroix]

Some materials will - if formed into a long enough (in relation to diameter) fiber - generate a charge, either due to mechanical interaction (wind friction) or simply movement through the earth's magnetic field(very long fiber needed for that).

It's similar to charging a ruler by rubbing it against a wool sweater. I'd guess spider silk would behave similar.

And it's less 'anti-gravity' but more like one of these one magnet hovering over another things, if I understood it correctly. Their charged nets float in the electrostatic field of the Earth.

[Elheru Aran]

And it's less 'anti-gravity' but more like one of these one magnet hovering over another things, if I understood it correctly. Their charged nets float in the electrostatic field of the Earth.

Yeah, the Earth is so big that its magnetic force is spread out over a massive surface area from what I understand. Thus anti-gravity via magnetic interaction with the Earth itself would only work on such a small scale as spiders using spider-silk to hover, which is further abetted by the wind catching them and moving them around. I want to say that if you were trying to do anti-gravity by pointing a magnet at the Earth, either it needs to be super-tiny (we're talking like... baby spiders here, not adult spiders, those buggers are *tiny*) or super-huge (as in... I dunno, size of a continent?). I'm probably wrong though...

[cadbrowser]

Their charged nets float in the electrostatic field of the Earth.

Right, and if you remember in the article that they mimic their natural behavior in an artificially charged field. That's all well and good, but how?

The surface of the earth is negatively charged; the atmosphere is positively charged. Like charges repel. So, if the spider silk has its own electrical charge, it would be negative, right?

Would that be why they tiptoe when they balloon? To get as high as they can so their strands are pulled up out of the negative field of the surface? Or would that practice give them the placement needed for the Earth's negative charge to repel them upward and then the positive charge and wind conditions continue to attract them and keep them aloft?

Atmospheric electricity - Wikipedia
Thunderstorms act as a giant battery in the atmosphere, charging up the ionosphere to about 400,000 volts with respect to the surface. This sets up an electric field throughout the atmosphere, which decreases with increase in altitude. Atmospheric ions created by cosmic rays and natural radioactivity move in the electric field, so a very small current flows through the atmosphere, even away from thunderstorms. Near the surface of the earth, the magnitude of the field is on average around 100 V/m.
Source

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And it's less 'anti-gravity' but more like one of these one magnet hovering over another things, if I understood it correctly. Their charged nets float in the electrostatic field of the Earth.

Yeah, the Earth is so big that its magnetic force is spread out over a massive surface area from what I understand. Thus anti-gravity via magnetic interaction with the Earth itself would only work on such a small scale as spiders using spider-silk to hover, which is further abetted by the wind catching them and moving them around. I want to say that if you were trying to do anti-gravity by pointing a magnet at the Earth, either it needs to be super-tiny (we're talking like... baby spiders here, not adult spiders, those buggers are *tiny*) or super-huge (as in... I dunno, size of a continent?). I'm probably wrong though...

Don't forget too that one could levitate a frog with a magnetic field (~16 Teslas) due to diamagnetic levitation.

[cadbrowser]

In a different, yet somewhat related article, I also came across this that I thought was pretty fascinating:

Spider spins electrically charged silk

In their quest to make ultrastrong yet ultrasmall fibers, the polymer industry may soon take a lesson from Uloborus spiders. Uloborids (pictured) are cribellate spiders, meaning that instead of spinning wet, sticky webs to catch their prey, they produce a fluffy, charged, wool-like silk. A paper published online today in Biology Letters details the process for the first time. It all starts with the silk-producing cribellar gland. At 60 micrometers, it is among the smallest silk glands ever observed and is covered in microscopic spigots that produce a low-viscosity liquid silk. In contrast with other spiders, whose silk comes out of the gland intact, scientists were surprised to discover that uloborids’ silk is in a liquid state when it surfaces. As the spider yanks the silk from the duct, it solidifies into nanoscale filaments. This “violent hackling” has the effect of stretching and freezing the fibers into shape. It may even be responsible for increasing their strength, because filaments on the nanoscale become stronger as they are stretched. In order to endow the fibers with an electrostatic charge, the spider pulls them over a comblike plate located on its hind legs. (This also gives the thread its wool-like appearance.) The technique is not unlike the so-called hackling of flax stems over a metal brush in order to soften and prepare them for thread-spinning, but in the spider’s case it also gives them a charge. The electrostatic fibers are thought to attract prey to the web in the same way a towel pulled from the dryer is able to attract stray socks. Next, researchers plan to test the silk for strength, as natural silks offer advantages over synthetics in terms of toughness, processing efficiency, and environmental issues.

Posted in: BiologyPlants & Animals
doi:10.1126/science.aaa6405

[Sea Skimmer]

That's pretty interesting to read. Processing the fibers under tension is a major part of how modern ultra high strength armor fibers are produced, and a major technological hurdle that's holding back the M5 fiber and one or two other theoretically extremely strength synthetic fibers from being yet practicable for mass production. The machinery that needs to tension them breaks too easily from fiber tangles. This might seriously cause a breakthrough in that kind of technology if it can lead to a totally different manufacturing approach.

The problem with spider silk proper remains while we have no trouble making huge amounts of it now, it hardens up after its produced until it gets so hard it cracks up after a few months. Research is yet to find the right gene splicing method to stabilize it, the genes they do add end up being dropped out of the spider/goat already modded to make spider silk DNA too quickly or else fail to produce consistent results. Apparently its made progress though, just not enough progress.