In mid-2013, Georgia Tech chemistry graduate student Troy Alexander snapped a photo of a tiny fence structure with a spire in the middle, intricately woven and attached to a blue tarp located near the Tambopata Research Centre lodge in the Amazonian jungle of Peru.
The pictures and speculation promptly did the internet rounds, and the tiny structures—which can be found on plenty a tree trunk in that part of the jungle—were affectionately dubbed ‘silkhenges’. The rings are usually just a couple centimetres in diameter. Experts weren’t sure what animal could possibly be responsible for these fenced rings, although spiders were floated as a leading theory (some people did think it could simply be a hoax).
Just six months later, entomologist Phil Torres led an expedition back to Tambopata to gather more intel, and the team confirmed the silkhenge was indeed a pointy spider egg sac erected in the middle of a fenced enclosure. Photographer Jeff Cremer even caught footage of a tiny spider clambering around the fence.
Now, Torres has released a video of the spiders actually emerging from the egg sac. To their knowledge, it’s the first time this event has been captured—and luck was certainly involved.
In May this year, Torres and his colleague UC Berkeley PhD student Aaron Pomerantz were in Yasuni National Park in Ecuador, where they found several more of the silkhenge structures. They brought a couple of them back to their field station.
“It was purely dumb luck that we had a camera on it right as it was hatching,” says Torres. “I happened to be taking a photo of it sitting on our desk when suddenly I saw part of it moving. We quickly realised what was happening and quickly got very excited.”
In the video, you can hear both men excitedly exclaiming as they watch the first of the tiny orange spiders crawl out of the silk cocoon encasing the eggs. Three spiders hatched out of this particular egg sac.
Witnessing this event enabled the scientists to use one of the hatchlings for a DNA sample. So far there’s not enough data to establish whether this is an entirely new species of spider or one that has previously been described.
Torres does point out that the spiders aren’t necessarily rare—they simply haven’t been studied in great detail until now.
“They are much more common than most people think,” he explains. “It’s just there are so few people out there looking for them that in reality they’ve only been observed maybe a few dozen times at most.”
Torres has heard reports of silkhenges from all over South America, including Brazil, French Guiana, and Ecuador, where these latest specimens hail from.
"It will likely be years until we get an answer"
As for the purpose of the silk fencing around the eggs, it continues to be a mystery, since the researchers didn’t witness the hatched spiders actually using the enclosure for anything.
Back in 2013 the team put forward several hypotheses on the purpose of the structure, although so far there is no strong evidence to support any of these. Having noticed some mites trapped inside a ring, they thought it could perhaps serve as an enclosure for an easy food source once the spiders have hatched. Alternatively, it could be there to fend off ants that would see the spider eggs as a delicacy.
“This end of the timeline of the structure doesn’t seem to hold any significance for the spider’s survival, so it must be significant elsewhere,” says Torres. “We still hold our hypothesis of anti-predation or anti-parasitism, but who knows?”
“It will likely be years until we get an answer, but hopefully sooner.”
Header image: Troy Alexander / Tambopata Research Centre