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A few researchers at the University of Trento have found that some spiders biased its use to take prey off the ground. In their paper published in Journal of the Royal Society Interface, Gabriele Greco and Nicola Pugno describe experiments with two species of spiders, Steatoda paykulliana and Steatodatriangulosa.
Previous research has shown that many species of spiders are capable of catching prey that is much larger than they are – in some cases 50 times as massive. But how they do this has not been well studied. In this new attempt, the researchers conducted experiments in which they captured videos of spiders in boxes to discover their secrets.
The boxes were just big enough to use the spiders as support for web building. Each of the spiders in the experiments was given time to build its web, and the researchers placed a large variety of American cockroaches in the box where it quickly became entangled in the lower part of the spider web. And that was when the action began. The researchers found that the spiders would repeatedly twist a length sideways, stretch it slightly and then paste one end of it on the cockroach and the other on an upper part of the web. The spider used its own body weight to stretch the side like an elastic band. As the spider attached more wires to the cockroach, it was eventually lifted completely off the floor, making it impossible to escape. The spider binds the cockroach in its place, injects it with poison and then waits for it to die so that it can digest its meal.
Looking more closely at the spider, the researchers found that the spiders pulled the systring to just the right tension – too much, and they would lose their elasticity, too little would mean wasted effort.
According to the researchers, this is the first time spiders have been observed catching much larger prey – and it also demonstrates another way spiders use webs to overcome their relatively small and light bodies to catch large prey.
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Gabriele Greco et al. How spiders hunt heavy prey: the vortex web as a pulley and spider’s mechanics observed and quantified in the laboratory, Magazine for the Royal Society Interface (2021). DOI: 10.1098 / rsif.2020.0907
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Quotation: Spiders use biased silk to lift prey off the ground (2021, February 3) on February 3, 2021 from https://phys.org/news/2021-02-spiders-pre-tensioned-silk-hoist-prey. html
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