Even small spiders can kill large prey, but how do they bring them back to their webs? Image credit: MiQ / Shutterstockcom
Depending on your persuasion, the images of spiders lifting prey apparently much larger in size will either impress or terrify you (someone remembers the opossum hunter?) Spider silk is renowned for its strength, but even armed with a nylon rope, most of us would have a hard time pulling a bison over a ledge, so how do little spiders do it?
New research published in the Journal of the Royal Society Interface solved this puzzle after studying the lifting power of five different spiders from two species of Theridiidae spiders: Steatoda paykulliana and Steatodatriangulosa Watching the canvas slingers in action, they realized that these tiny engineers were able to lift prey to an inescapable height by creating a system of pulleys made up of many threads called an entangled web.
Co-authors Gabriele Greco and Nicola M Pugno placed a spider and a cockroach (Blaptica dubia) in a plastic-come-thunderdome box and recorded the drama that followed.The box was lined with black paper to make it easier for the camera to detect what was going on with the spiders' light silk ropes Researchers say it is the first time that the lifting mechanism of spiders has been studied in this way, and the new approach revealed some pretty fascinating silk spinning techniques.
The first step was to immobilize the preys a la Shelob by wrapping them in silk and poisoning them so that they did not squirm during the arduous lifting process.. The spiders then released a slightly different type of silk that came from the main ampulla gland and, like a rubber band, could be used as is or stretched. Records revealed that when the spiders began to build the tangled web, going from the prey to a higher place near the spider's den, they only used this special silk, that was pre-stretched to attach to the prey
Then came the uprising, who saw the spiders move up and down the tangled web connecting more and more pre-stretched threads as they went. As these are built in numbers, the elastic potential of the pre-stretched yarns was able to reach the lift in the same way that an elastic band reverts to its smallest size when released. The mechanism is similar to that seen in old-school elevator pulleys and made it easier for the spider to lift its prey with each additional thread.. The battle was considered over once the cockroach reached the highest point of the tangled web near the spider's den.
«Spiders in the Theridiidae family display a peculiar behavior when hunting extremely large prey», wrote the study authors. «They raise the career, preventing him from escaping, by attaching pre-stretched silk threads«Understanding the mechanisms of the use of silk is a vital line of research for both the innovation of new technologies and materials, but also as a means of better understanding the evolution of silk spinners in general. The researchers say their findings provide «further proof of the important role of silk in the evolution of spiders, in particular how spiders can stretch and use it as an external tool to overcome the limits of their muscles and capture large mass prey, eg 50 times the mass of the spider”
Skillful handling of silk displayed by these tiny spiders demonstrates the transformative power of working smarter, no harder If only the protagonists of The Gigantic Turnip had known
Spider, silk, spider web tangle, scientist
News – FR – Tiny spider engineers use silk pulley systems to lift prey 50 times their weight