This homemade spider has no venom … but she has a "sling"

Does the idea of ​​a spider using his web to propel himself at high speed gives you the willies? So be forewarned: the weaver triangle spider (Hyptiotes cavatus) just do that. Making it the only known creature, apart from humans, to employ a strategy known as "external power amplification," reveals a new study.

The concept of external power amplification is simple. Basically, an animal uses an external device (in this case the spider web) to store energy, as a person who stores energy in an arc with an arrow pulled back . Once the energy is released, the spider is projected forward like a slingshot, far exceeding the speed at which the arachnid could otherwise move.

This clever trick helps the spider survive. The weaver's triangle spider has no venom, so she used this method to help quickly catch prey that settle on her web, the researchers said. [Goliath Birdeater: Images of a Colossal Spider]

To study the creature, the scientists collected triangular wild spiders from the United States and Canada, and took them to the laboratory, where they were housed in terrariums and filmed with high speed videos while they were on the ground. they hunted their prey.

The videos revealed that after the spider built a triangular web, she pulled back to the corner of the canvas, where the long lines of her web came together. Then you need the Web anchor line, the main thread that connects the web to something stable, like a branch, and cuts the line in half.

Then the spider makes his turn: she uses her body to fill the cut and now loose linen thread. He holds the far end (the end closest to the branch) with his hind legs and front with his forelegs. Then the spider walks back "in a" leg-on-leg "motion, pulling the canvas taut," the researchers wrote in the study.

When the spider recedes, it essentially stores energy on the Web, much like a little kid who pulls a sling. The spider can wait like that for hours. Then, when the spider feels a stimulus on itself or on the canvas, it releases the rear anchor line and moves forward with alarming speed.

"All this stored elastic energy causes a recoil and it [the spider and the web] It's just as if you were letting the elastic drop, "said Daniel Maksuta, co-researcher at the study, PhD student in polymer science at the University of Toronto. Akron, in Ohio. " It really works too. [If] the prey is massive compared to the web and the spider, the web is thrown on all around. So it's like that [the prey] becomes all entangled. "

The maneuver is so fast that the spider can be thrown forward at accelerations of about 775 meters / second (2535 square feet), the researchers discovered.

"The spider and the web move a lot before the prey really begins to move," Maksuta told Live Science. In other words, the prey does not even know what hit it and, if so, it is too late.

The little spider then seeks to trap the prey with more iterations of this method until the unfortunate victim is completely wrapped in silk. All of this is done without the spider having to come close to prey, which protects the eight-legged creature from a possible injury.

"It's good enough to catch prey without having to touch it, unlike a lot of spiders," Maksuta said.

Other animals use power amplification, but this is usually powered by their own muscles, which means that it is not external to that of the spider. Classical examples are the flea jumping mechanisms, frog insects and frogs; the death blow of mantis shrimp; and the projection of the language of the chameleons, the researchers wrote in the study.

"We can not really underestimate the technological progress of the organizations," said Maksuta. "They are creative."

The study was published online on May 13 in the journal Proceedings of the National Academy of Sciences.

Originally published on Science live.