Q&A: New Spider Weaves Spider-Shaped Web

Wildlife biologist Phil Torres recently discovered a new species of spider in the Amazon that would take first prize at any costume party. This tiny five-millimeter-long spider builds a decoy spider around five times its size to scare off potential predators.

After describing his find on his blog, Torres sat down with Weird & Wild to share the story of how he came to find this new species of spider.

Q: How did you first spot this spider?

A: I was at the Tambopata Research Center in Peru (map), which is a ten-hour canoe ride from the nearest town. I was leading a rain forest expedition with a videographer, and one of them called me over and said “Hey, look at this. It looks like a dead spider.” We went over there and realized pretty quickly that something interesting was going on.

It looked like a spider that had been killed by a fungus—it had this flaky, evaporated look to it. But then the thing started moving, and we realized that there was something alive in there. There was another one near it with a similar design. We put two and two together and realized that this was a fake spider. There was a small spider living behind this fake spider constructed out of debris. (Also see Photos: World’s Biggest, Strongest Spider Webs Found.”)

Had anyone previously documented this spider?

After freaking out a bit, we took a bunch of pictures to really document what we had seen. I contacted Linda Rayor, one of my professors from Cornell who does a lot of spider-behavior research, and asked if she had seen anything like this. She said she hadn’t. She passed the photo around, and I contacted a few more places, and everyone said that no, they had never seen anything like it.

Talking to Dr. Rayor, we determined that this spider was probably in the genus Cyclosa, because they are also known to make structures in their webs, but the other decoys are a bit more simple.

Trojan horse? A new species of spider hides behind a giant decoy it builds out of debris. Photo courtesy Phil Torres.

The decoy made by this new spider is much more detailed and difficult to construct because it has the body structure and the leg structure. The first decoy we came across looked really good—it had eight legs, and it really looked like a spider hanging in its web. But we saw other decoys that had four legs, or seven legs, or other numbers. From afar, though, they all really look like spiders, and it’s probably enough to fool predators.

So is that the purpose of the decoy? To confuse predators?

From what we know about other Cyclosa, yes. If you’re a big predator looking to feed on a big spider, you might get close and realize that Oh, there’s only a small spider there that’s not worth the effort. A smaller predator looking to eat a small spider would see the decoy and think it was trying to go after a much bigger spider. (See Largest Web-Spinning Spider Found.”)

The variation in decoy leg numbers could mean that the system is still evolving and is not quite perfect. It could also mean that the variation is beneficial—a lot of times, predators can learn patterns very quickly. If they only made one type of decoy, the predators could learn to associate the real spider with the decoy.

What needs to be done to establish this as a new species?

I need to collect specimens and send them to an expert on Cyclosa. Literature will be examined to see if the spider can be identified based upon its morphological characteristics. If it can be identified, it is likely not a new species, but if it can’t be identified then we are dealing with a new species. The key is to compare certain physical characteristics, like the male genitalia, to determine the species’ status.

Carrie Arnold is a freelance science writer living in Virginia. When she’s not writing about cool critters, she’s spending time outside, drinking coffee, or knitting.

Wildlife

Carrie is a freelance science writer living in Virginia. When she's not writing about cool critters, she's spending time outside, drinking coffee, or knitting. You can visit her website at http://www.carriearnold.com