D. Kucharski K. Kucharska / shutterstock.com

Twitter Worked Out That Jumping Spiders Can See The Moon

What scientists get up to when there's a spider in the lab.

AMY THOMPSON
23 JUN 2017
 

Brace yourselves, arachnophobes, as we dive into a topic that's equally as terrifying as it is intriguing: jumping spiders can see the Moon!

In the midst of a weird spider infestation, one scientist on Twitter managed to pull together a collective team of brains to explain and experiment with the fact that these spiders would even chase laser pointers, and the reasons why.

 

In this recent Twitter thread, researchers explained that certain spiders are made to be stargazers. Equipped with sensitive visual systems, some arachnids can resolve the Moon and other celestial objects - including the Andromeda galaxy - in the night sky.

Should they choose to look up of course.

So where did this Twitter lesson come from? Jamie Lomax, an astronomer at the University of Washington, tweeted that spiders were raining down on her desk.

Responses to that tweet included using nukes and fire on the little guys, but instead she opted to try a different approach: use laser pointers to herd them.

Lomax quickly determined that the rappelling arachnids were a type of jumping spider, and the tiny creatures are prevalent in the Pacific Northwest.

Alex Parker, astronomer at the Southwest Research Institute, tweeted that jumping spiders have been known to chase laser pointers, much like a cat would. So Lomax and fellow astronomer Emily Levesque - a colleague with an office down the hall, also occupied by the little jumpers - decided to test this out.

The duo tested both red and green laser pointers and found that the spiders went crazy for the green lasers and were less impressed, albeit slightly interested in the red laser. The results garnered quite a bit of attention and eventually some spider experts caught wind of the happenings and chimed in.

 

"Spider Twitter just showed up to explain to space Twitter why our jumping spiders are following our laser pointers," Lomax tweeted.

The Zebra spiders, like all jumping spiders, are visual hunters and were attracted to the moving lasers like they would be to prey. Their eyes have two types of special light-detecting cells that are perfect for sensing ultraviolet light as well as green light.

As such they can probably see the red light, but it appears as a dimmer form of green, explaining the difference in the spider's reactions.

It wasn't long before Nate Morehouse of the University of Cincinnati who studies spider vision was looped into the discussion. He explained that jumping spiders aren't like your typical web spinners, they're much cooler.

 

Jumping spiders rely on their keen vision to catch their prey. He explained that they can see as well as creatures hundreds of times larger: like dogs, cats, and even pigeons.

This is all thanks to a special set of telescopic eyes that bend light in order to enlarge images - just like, wait for it - a Galilean telescope!

Like the telescope first used by the famed astronomer in 1609, the spider's eyes are essentially tubes with a lens at each end. One lens collects and focuses the light, while the other spreads it out and enlarges the image, allowing the spider to see a lot of detail for its size.

The visual acuity (how well the spider can differentiate between objects) of jumping spiders is good enough to allow them to see objects that are 0.07 degrees apart. The full Moon spans roughly 0.5 degrees, making it easy to spot if a spider decides to look up, Morehouse explained.

He went on to say that it all depends on how sensitive they are to differences in brightness. Some spiders may even be able to make out the dark patches on the lunar surface, but all could tell that the Moon was round.

With a few quick calculations, other scientists chimed in, disappointed that both Mars and Jupiter were too faint for the spiders to see.

Then Morehouse dropped another interesting nugget of spider trivia: the ogre-faced spider (yes, it's probably as terrifying as it sounds) could see our closest galactic neighbour, the Andromeda Galaxy.

These big-eyed beasties are nocturnal and as such, their eyes are especially sensitive to lower levels of light, which is ideal for galaxy gazing. Andromeda spans three degrees of the sky, but it's incredibly dim - even humans can have a difficult time spotting it.

Lomax has since tweeted that it's been a week since she's seen any spiders in her office, so perhaps all this talk of stargazing sent them off in search of a good place to stare up at the night sky.

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