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S. I. Han

This spider turns its web into a slingshot, flinging itself at prey

When we think of how spiders hunt, we usually picture intricate webs that can ensnare passing insects. But the triangle weaver spider (Hyptiotes cavatus)—native to the United States and Canada—does something special: It creates a slingshot with its silk web to catapult itself forward and capture its prey.

To watch the spiders at work, scientists recorded them using high-speed videos. They saw that the arachnids stretch and tighten their silk threads, using their body as a bridge between the anchor line and the web (as seen in the photo above) and can hold the web under tension for hours on end. When prey wanders into the web, the spider releases its hold and uses the silk’s stored energy to shoot forward at extraordinary speeds, the researchers report today in the Proceedings of the National Academy of Sciences. The web then wraps around the prey from all directions, blocking any chance of escape.

According to scientists, this is the only known example of an arachnid using a device to boost its power—thus revealing a new function of spider silk.