Spider Building Spider Decoys Discovered in Peruvian Amazon

Fake spiders act as decoys, forming part of a defense mechanism designed to confuse or distract predators. Credit: Phil Torres

Discovered at the Tambopata Research Center in the Peruvian Amazon, a spider belonging to the genus Cyclosa is capable of producing elaborate, fake spider decoys. It hangs them in its own web and shakes the web, furthering the illusion.

The spider is believed to be a new species, and crafts a larger spider from leaves, debris, and dead insects. The genus Cyclosa includes other sculpting spiders, but this is the first that has been observed to build a replica with multiple legs and to use a web-shaking behavior.

A decoy spider hangs below its much smaller builder, suspected to be a new species in the genus Cyclosa. Credit: Phil Torres.

The fake spiders serve as decoys, as part of a defense mechanism meant to confuse or distract predators. Within a 1-square-mile (2.6-square-kilometer) area, researchers found more of these spider-building spiders. They could be locally restricted, but there could also be millions of these spiders in the rainforest. Some of the decoys looked realistic, while others looked more like cartoon octopi.

Other spiders of the genus Cyclosa build decoys that are clumpy and made out of multiple little balls built from egg sacs, debris and prey, rather than something that actually looks like another spider.