fir0002 | via Wikimedia Commons // CC BY-NC 3.0
fir0002 | via Wikimedia Commons // CC BY-NC 3.0

The Strength of Spider Web Glue Is Affected by UV Light

fir0002 | via Wikimedia Commons // CC BY-NC 3.0
fir0002 | via Wikimedia Commons // CC BY-NC 3.0

As you trick or treat today among the ubiquitous giant spiders posed in elaborate fake webs, take a moment to ponder the extraordinary talents of our real arachnid friends. Consider this, for example: Real spiders spin webs covered in an extremely strong natural glue that all but seals the fate of unfortunate insects that bumble into the trap.

Now, scientists are yielding new data about the varying degrees to which different species’ web glue can resist damage by ultraviolet radiation—information that may eventually lead to the development of new, more environmentally friendly adhesive products.

For years, researchers in biologist Brent Opell’s lab at Virginia Tech have been stalking spiders and collecting their webs in order to learn more about how the glue works. They know that spiders secrete tiny droplets containing a special protein as they spin their silken threads. The droplets become sticky once exposed to air, creating the glue-like substance.

That glue’s stickiness can be affected by a variety of conditions, including humidity and temperature. And in a new study recently published in the Journal of Experimental Biology, Virginia Tech scientists report that ultraviolet radiation also affects spider glue—some much more than others.

To test the effects of ultraviolet B (UVB) radiation, the scientists collected fresh webs made by five different species of so-called orb weaver spiders, which make classic wheel-shaped webs. They then harvested the sticky droplets from the web, and exposed them to varying intensities of UVB rays.

Some webs belonged to spider species that prefer to catch their prey in broad daylight. The others came from species that hunt at night or in forests, where webs receive little or no direct sunlight.

“We shocked some of them with UVB radiation under a light like what you might find in a tanning bed, kept some in dark, and then looked at how the drops responded after being subjected to different levels of radiation,” Sarah Stellwagen, the study’s lead author, told mental_floss.

Stellwagen and her team discovered that the glue of spiders that hunt in daylight not only resisted damage from UVB rays much better than those of the nocturnal and shade-loving forest spiders, but was slightly enhanced by it.

What exactly makes some spider web glue better able to withstand UVB rays remains a mystery, at least for now.

“It could be something happening with the protein that UVB rays actually strengthen it [in some species],” Stellwagen said. “Just like the dentist uses UV light to strengthen the bond that they fill your teeth with.”

No one has yet made an adhesive based on the spider’s glue. First, scientists need to better understand the properties and function of the protein from which the glue is created, how it varies from species to species, and how other environmental factors may affect the glue’s stickiness.

But the fact that spider glue is biodegradable, stable for long periods of time, and extremely strong make it a good candidate for biomimicry—the creation of materials inspired by biological substances and processes occurring naturally in plants or animals.

With further study, material scientists could construct new molecules that have similar abilities to resist UVB radiation. That could eliminate the need for UV-stabilizing chemicals that prevent degradation caused by light in manmade adhesives.

“It definitely has uses, and being a green product, it could replace some other products that cause pollution,” Stellwagen said.

8 Ways Spiders Are Creepily Clever

You may already know that spiders can spin intricate webs and poison their prey. But that doesn't even begin to cover the all the sneaky abilities spiders have adapted to become the most fearsome organisms on eight legs. Here are some of the tricks spiders use to catch their meals while avoiding becoming dinner themselves.


Spidey-senses weren't just invented for comic books. Jumping spiders in real life have sharp eyesight and excellent hearing to make up for their inability to spin webs. Scientists long assumed that spiders couldn't hear because they don't have ears. But as researchers reported in a 2016 study, jumping spiders can "hear" perfectly fine—they just use the super sensitive hairs on their legs to do so. These same spiders can also see surprisingly well, as astronomer Jamie Lomax demonstrated when she used laser pointers to lure them away from her desk like they were tiny cats.


The fact that the jumping spider species Myrmarachne formicaria tricks predators into thinking it's an ant by mimicking its appearance isn't a new discovery. But exactly how it achieves this was unclear until recently. According to a Harvard study published in the Proceedings of the Royal Society B, the spider pulls off this deceptive stunt while using all eight legs to walk. During its performance, it takes 100-millisecond pauses to lift its front two limbs to its head so they resemble antennae. The switch is so fast that to a human looking from above, the spider appears to simply be walking with its back six legs while lifting its front legs off the ground. Scientists had to use high-speed cameras to prove this wasn't the case. 


Despite lacking ears, spiders have some impressive musical talents. They treat the strands of their webs like the strings of a guitar, tuning them just right so they can detect certain vibrations. For their study published in the Journal of the Royal Society Interface, researchers from the University of Oxford and Charles III University of Madrid observed garden cross spiders maintaining their webs. They learned that adjusting the tension and stiffness of the silk allows the spiders to sense frequencies they can recognize. One signal might mean that prey is near, while another could be connected to structural issues with the web.


Spider disguised as bird poop.

Min-Hui Liu et. al, Scientific Reports // CC BY-NC-ND 3.0

Camouflage is not unique among arachnids, but orb weaver spiders may win the prize for the most memorable disguise. In its juvenile stage of life, the spider will surround itself with a thick, white material in the center of its web. Its whitish abdomen blends into the "decoration," making the spider appear as if it's buried in a splatter of bird droppings. The unappetizing look is usually enough to convince predators to look elsewhere for a meal that's easier to stomach.


Spider with web between it's legs.

Chen-Pan Liao, Wikimedia Commons // CC BY-SA 3.0

Bigger isn't always better when it comes to webs. Take the net-casting spider: The silken trap it uses to snare food is small enough to fit between its limbs. The spider poops out a pale "target" onto the forest floor and then hangs above it waiting, sometimes for hours, for an insect to come along and trigger a "trip wire" connected to the ground. Once that moment comes, it wastes no time lunging at its prey and enveloping it in its web. It then bites and paralyzes its prey before commencing the feast.


If all else fails, at least tarantulas have their spear-like hairs to fall back on. A tarantula deploys its "urticating hairs" when it feels threatened. By grinding its back legs against its abdomen, it's able to shoot the barbed hairs at its target like a shower of tiny throwing stars. You don't have to be a predator to trigger this defense mechanism, as many tarantula pet owners have found out the hard way.


When most spiders need to escape a dangerous situation, they rely on their eight limbs to scurry them to safety. The golden wheel spider curls up its body and rolls down hills to make an even speedier getaway. This type of spider is native to the Namib Desert in southern Africa, where steep, sandy dunes are abundant. When it's tucked into a ball, the spider can reach tumbling speeds of 3.2 feet per second.


Even without gills, spiders have adapted some pretty clever ways of surviving underwater for long amounts of time. The diving bell spider weaves web balloons that extract dissolved oxygen from the water around it while filtering out carbon dioxide. Using this improvised scuba suit, the spider can last a whole day before it needs to come up for air. Then there are wolf spiders, which use a much more dramatic survival tactic. A 2009 study found that marsh-dwelling varieties of wolf spiders appear to drown after being submerged for extended periods. But once they're placed on dry land, they twitch back to life. Slipping into a coma underwater is how they're able to evade death.

We May Be Hardwired to Fear Snakes and Spiders

Just the mere sight of a daddy longlegs or garter snake can prompt shrieking and shoe-throwing, even though not everyone has had bad experiences with creepy-crawlers. Are we naturally predisposed to hate tiny critters that scurry and slither? A new study suggests so, according to a video from National Geographic (below).

The video highlights a new study by a team of researchers from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, Germany, and Uppsala University in Sweden, who measured the pupils of 6-month-old babies as they stared at pictures of flowers and fish, or snakes and spiders. Human pupils naturally enlarge as a response to danger—and sure enough, the babies' eyes dilated more frequently when they were exposed to the garden pests. This suggests that our widespread dislike of spiders and snakes might be ingrained in us (although the time your bunkmate hid a spider in your sleeping bag at camp probably didn't help, either).

You can check out the full study online in the open-access journal Frontiers in Psychology. And to help squelch your fears, here are some common (yet wildly inaccurate) myths about spiders, and some dispelled misconceptions about snakes.

[h/t National Geographic]


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