ATLANTA – For people who are afraid of spiders, the slingshot spider is the sort of stuff nightmares are made of. Although the slingshot spider is tiny, only about one millimeter long, the way it catches prey is particularly creepy. A new study reveals these tiny crawlers don’t just leap at their victims, they take their web with them too!
The study by the Georgia Institute of Technology, focuses on understanding slingshot spiders’ webs. Researchers say this remarkably fast slingshot mechanism allows the spiders to propel themselves 100 times faster than the acceleration of a cheetah. Their results in the journal Current Biology may help shed light on ways to create ultrafast tiny robots and other devices.
“Unlike frogs, crickets, or grasshoppers, the slingshot spider is not relying on its muscles to jump really quickly,” assistant professor Saad Bhamla explains in a university release. “When it weaves a new web every night, the spider creates a complex, three-dimensional spring. If you compare this natural silk spring to carbon nanotubes or other human-made materials in terms of power density or energy density, it is orders of magnitude more powerful.”
Launching into action
Slingshot spiders, known to scientists as Theridiosomatid, are a Peruvian spider that hunts for prey at night. Each night it creates a 3-D cone-shaped web with a piece of web silk in the middle that acts like a tension line.
To catch prey, the spider pulls on the piece of silk with its front legs while holding on to the main web structure with its back legs. When it senses prey, it releases the line and catapults itself toward its meal. If the spider is successful, it wraps the victim in silk and eats it. If not successful, it pulls on the piece of silk to reset the tension on the web.
To study the slingshot spiders’ web structure and mechanism, the team traveled to the Tambopata Research Center. Due to a lack of electricity in the area, the researchers were faced with intense darkness. This darkness also made them wonder how the slingshot spider can sense prey and properly align its slingshot.
Study authors think the spiders likely use an acoustic sensing mechanism. Their theory on sound seems to check out. When researchers snap their fingers, it tricks the spiders into catapulting their web.
Slingshot spiders do a lot of work for every meal
The scientists are also wondering how these creatures can hold the web while hunting. They estimate that stretching and holding the web requires at least 200 dynes (a unit of force) — which is a huge amount of energy for a tiny spider.
“Generating 200 dynes would produce tremendous forces on the tiny legs of the spider,” Bhamla says. “If the reward is a mosquito at the end of three hours, is that worth it? We think the spider must be using some kind of trick to lock its muscles like a latch so it doesn’t need to consume energy while waiting for hours.”
The scientists were hoping to continue their research in Peru this summer, but their plans have been thwarted by the coronavirus. They hope to continue their research as soon as possible.
“Nature does a lot of things better than humans can do, and nature has been doing them for much longer,” adds researcher Symone Alexander. “Being out in the field gives you a different perspective, not only about what nature is doing, but also why that is necessary.”