Three 8-legged mysteries to keep you up at night

As an entomologist, one of the things that keeps me up at night is what I call “jungle mysteries.” They are everywhere. If you walk around the rainforest enough, you end up finding animals or structures that you—and sometimes nobody in the entire world—can quite figure out. My last few years of working heavily in the Amazon, I’ve been particularly focused on what I’ll call eight-legged mysteries—attempts to explain odd behaviors we’ve found in spiders that have never been seen before in any animal, let alone just arachnids. Can we be the first people in the world to crack the case? That’s what drives me, my colleagues and thousands of other scientists working in these environments to trudge through long, hard, mosquito-bitten hours in the field. On a recent expedition, I was joined by entomologists Lary Reeves and Geena Hill from the University of Florida. We went to Peru to solve a few jungle mysteries, and ran into a couple more while we were at it.

The Tambopata Wildlife Reserve in Peru is one of the most pristine locations to observe and search for new species. (TechKnow/Al Jazeera America)

An Odd Circular Structure First discovered in August 2013 by Troy Alexander, a biologist friend of mine, this structure was truly unique in the natural world and no one—not amateurs or experts around the world—knew what it was. Images of this structure went viral on Reddit and received a lot of media attention, so the pressure was on for us to figure what it was, and who made it. With theories ranging from fungus to slime molds to spiders to a hoax, we spent hours meticulously surveying the one tiny island on the Tambopata River in which the circular structure was previously found. Over the week we were there, we didn’t manage to find anything making it but we did hatch something out of it: a tiny spiderling.

A mysterious circular structure formed by an unknown type of spider. (TechKnow/Al Jazeera America)

So, it’s definitely a spider—but what kind we are unsure. While we at least have solved one part of the mystery, much remains. We hypothesize that the circular fence may act as a defense against ants, and we found a possibility that the fence could also be attracting and capturing mites within for the spider to eat upon hatching. As far as we’ve been able to find out, this seems to be the first instance of a spider laying one single egg. They typically lay multiple eggs, ranging from a few to hundreds, in an egg sac. The internet first helped draw attention to this mystery, and it also helped deepen it: We received photos from Ecuador and Guyana and a report from Brazil all showing the same fence phenomenon. The mystery deepens.

Phil Torres and Lary Reeves observe the "decoy spider" in its web. (TechKnow/Al Jazeera America)

The Decoy-Building Spider Last year, we discovered a spider that actually makes a fake spider in its web. Using debris, prey carcasses, and its own molted exoskeleton, this spider builds a figure with what appears to be a body and legs. It’s the only known animal—besides humans—that can construct the figure of another animal from scratch. But why?

Our leading hypothesis is that it is done to confuse predators and help it avoid being eaten. Approach this spider too aggressively and it shakes the larger spider form back and forth, making it look like a much larger, more defensive, spider. While we still have much to learn, we did find out a lot about how quickly they can construct these decoys (almost overnight) and how the rainy season affects them (hint: it destroys their work). Another Mystery Appears... While searching for spiders one night we came across this mystery. The best way we can describe it is as a gel capsule attached to a leaf with an insect larva inside.

(TechKnow/Al Jazeera America)