These Spiders Built a Massive Decoy Spider Out of Carcasses

Ever see something spider-shaped out of the corner of your eye and panic, only to have it turn out to be something else? In the case of Cyclosa spiders, you might see a large spider sitting in its web and then realize it’s not a spider at all. Instead, it’s a big spider decoy made out of insect carcasses and other debris. But there is still a spider in that web, it’s just much smaller. The fake versions likely help keep predators away. But they probably still give people quite a fright.  

Cyclosa spiders are also called trashline orbweavers. It’s a group of nearly 200 species that live around the world. Many of them incorporate debris into their web but so far there’s only two known to design those decorations into decoy spider effigies.

Scientists only discovered both species about 10 years ago, one in the Peruvian Amazon and one in the Philippines that was first found around the same time. While the spider in Peru tends to build doppelgangers with legs pointing down, the one in the Philippines builds faux spiders with their legs spread out radially. Those two places are 11,000 miles of Pacific Ocean apart so it’s likely an example of convergent evolution, where similar pressure on the spiders caused them to evolve this trick to ward off predators.

A spider collects debris in the shape of a spider in the center of its web
National Geographic

Though they’re not my favorite subject, it seems like there are a lot of interesting spiders out there to write about. The only cute thing I’ve ever seen a spider do is twitch in its sleep while it dreams. Well, that and make friends with frogs. And the most horrifying video I’ve seen of spiders recently wasn’t really their fault. It was humans who turned dead spiders into gripping tools that are terrifying to see in action. So maybe spiders aren’t really that bad after all.  

Melissa is Nerdist’s science & technology staff writer. She also moderates “science of” panels at conventions and co-hosts Star Warsologies, a podcast about science and Star Wars. Follow her on Twitter @melissatruth. 

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