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Photograph by VirtualWolf, Flickr

What Halloween Decorators Know About Spiders (Oddly, a Lot!)

Here was my Halloween plan: not original, I know, but classic, effective, and cheap.

My front door, I decided, would become a lush, over-the-top spiderweb, a luxuriant Donald Trumpian display of muchness, which means … I would need two, maybe three, stretch-to-fit spiderwebs.

I don’t know the dimensions of my door (does anyone?), and I didn’t want to think about this for more than, oh, two minutes, so after a quick (and useless) trip to the Halloween section of my local drugstore, I jumped to the other web, the worldwide one, where I found (yes!) a nonflammable “Stretchable Spider Web” 12-pack for $10.99, with (yes!) a complimentary half-inch plastic spider, which (yes!) works out to about 90 cents per web (not including thumbtacks or tape). Good price. But—when I opened it—bad web.

It’s one of these …

I was hoping for a classic, top-of-the-line spiderweb with a cool hole in the middle and surrounded by radiating spirals of silk, like the ones you see on trees, bushes, and the cover of Charlotte’s Web, capable of having “Terrific!” or “Some pig!” written on them, what arachnologists call an orb web, like this …

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Photograph by George Grall, National Geographic Creative

But Halloween orb webs are pricey. Target wants $14 for just one. (It comes with lights, but still …)

Instead, what I got in my nonflammable 12-pack was a lesser design. They call them tangle webs or, worse, sheet webs, like the ugly one here …

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Photograph by Paul R. Sterry, Alamy

These messy, disorganized clumps are the work, I imagined, of low-rent “beginner” spiders who haven’t yet learned how to do it beautifully. So I was a little bummed. I even went to a couple of spider sites to see what evolutionary losers inspired my 12-pack.

But what I found shocked me.

Orb webs are not considered spider masterpieces. Not by spider scholars. Don’t be fooled by how beautiful, symmetrical, and lyrical they are. Spiders have moved on.

“More advanced spiders,” says Paul Selden, a spider paleontologist at the University of Kansas in Lawrence, “have gotten rid of [orb webs] and developed something else.”

It’s true. I found a bunch of papers that say orb webs are very ancient creations. These days, they’re considered “primitive.”

Turns out that webs like Charlotte’s require a fairly big spider (many spider species are small); worse, these webs need their spiders to stay close, which means they can be spotted and eaten by predators; still worse, they’re not that easy to navigate. Some of them have really sticky parts that can trap their spider. Which is why more highly evolved spiders have stopped making them.

So what are more evolved spiders making instead?

Unbelievably enough, they’ve moved up (up?) to sheet webs and cobwebs—the hideous things I found in my 12-pack!

An extensive survey of newer species found that the spiders that used to make orb webs have stopped, switched, and evolved into sheet and cobweb makers. Two of the fastest growing spider types, says biologist Jon Coddington, “are linyphiids (sheet webs) with 4,378 extant species, and theridiids (cobwebs) with 2,310 extant species.”

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Photograph by sogni_hal, Flickr

That means the little web you keep sweeping away in the corner of your garage or up in the attic, that sad little thingy that looks like it should stay in the corner, is—who would have guessed?–a considerably improved bit of spider design. Cobwebs, says science writer Sue Hubbell, are “more elaborately engineered, denser, safer for the spider and more efficient for trapping prey.”

So what if they’re ugly? Spiders aren’t trying to please me. They’re trying to get dinner. Ugly webs, apparently, are just better for spiders than beautiful ones, and if you doubt that, all you have to do is look at an evolutionary tree of spider webs.

Just tap on my “cover” tree (it’s a hyperlink that will take you to the tree I want you to see) and look for the orb webs. They’re not at the top … not at all …

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Drawing by Robert Krulwich

Which means I’m reconsidering the biological sophistication of the Halloween decoration industry. I don’t know how many arachnologists my local drugstore has on staff (zero?), but what they’re selling this year is biologically, and evolutionarily, top of the line. What’s more, you can get a dozen of these gems for the low, low price of 90 cents.

This is a great country we live in.