Mystery Solved: Weird Amazonian Web Towers Built By Spiders

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Back in September, GFR reported on some mysterious structures found in the remote Peruvian rainforest. A graduate student staying at the Tambopata Research Center found the structures and posted them on Reddit, where scientists and laypeople alike offered various theories about what made them. When no one could come up with any definitive answers, entomologists headed down to solve the mystery once and for all. And the good ol’ reporters at Wired followed them. It took some doing, but we finally have an answer: spiders. Yay?


The six-millimeter-wide silk structures are incredibly elaborate for being so small — they have a tall tower in the middle surrounded by something that looks like a fence. The creatures responsible put an awful lot of effort into them — about as much as the researchers who finally identified them. The team of entomologists led by Rice graduate student Phil Torres retraced the steps of the person who first found the structures. They found a whole bunch of the tiny structures on tree bark, leaves, and bamboo. Most were grouped together. Jeff Cremer, acclaimed wildlife photographer, took a bunch of awesome close-ups that revealed not only the intricacies of the structures, but also the mites that were crawling all over them. This discovery confused the scientists even more, given that mites generally don’t make silk, and given the size of the structures relative to the size of the mites.

Another would-be lead involved what looked like a broken egg sack at the bottom of one of the towers that had been knocked over. It didn’t make much sense for the tower to be an egg sack, though, and if it were, whatever made it would probably lay many more than one. Additional photos revealed similar sacs at the base of many of the structures, which the scientists realized may not have been egg sacs at all, as well as more mites. At this point, the team ruled out a few creatures that don’t make silk, but they still didn’t know what did make the structures.


After nearly a week in the rainforest, the researchers were getting ready to leave, still stumped by the mystery. That’s when a couple of eggs hatched and the scientists found two little spiders hanging out near the structures. The next day, a third one hatched. This means that the structure is some kind of nursery for spiders, but it still confounds the researchers, especially the behavior of the mother spider. They typically lay a whole slew of eggs, wrap them up, and protect them, much like other animal mothers. To build an entire structure for a single baby spider seems strange, but hey, weirder and more elaborate things have been built for babies.

Now the question is what type of spiders these are. While Torres and the other researchers will continue their examination, they think it could be a jumping spider (seriously, spiders do not need to be able to jump, on top of everything else) or the far more appealing “corpse” spider that hides its nests under the carcasses of their prey. Um…is there a third option here? I’m guessing it’s not a robot.