While most spiders are happy to spin a web and wait for dinner to come to them, the slingshot spider takes a more active approach, using its web to fling itself at its prey. For the first time, researchers have measured precisely how fast the arachnid flies. (Hint: It’s pretty fast.)
In Peru’s Amazon rainforest, there is all manner of impressive creatures, not least of which is the slingshot spider. This tiny arachnid builds a cone-shaped web equipped with a tension line attached to the center. Once the web is complete, the spider climbs down the tension line bringing the web with it by using its back legs. When it senses a nearby meal like a fly or mosquito, it releases its grip on the line, launching itself and its web backward at its prey, and, if it connects, it wraps the bug in silk until it’s dinner time. Then, the spider reloads the web using the tension line.
Even though the slingshot spider’s unusual hunting method was first described in a scientific paper in 1932, no one actually measured the speed at which the spider was traveling once launched. So researchers from the Georgia Institute of Technology headed to Peru’s section of the Amazon to find out.
Catch You Later, Cheetah
Using ultrafast cameras and kinematics (a science often called the geometry of motion), researchers determined that the spider can accelerate itself to the speed of about four meters (13 feet) per second. That’s 100 times the acceleration of a cheetah. It also produces the force of about 130 Gs, which is truly impressive because fighter pilots can only handle about 13 Gs before passing out.
“We wanted to understand these ultrafast movements because they can force our perspective to change from thinking about cheetahs and falcons as the only fast animals,” said Saad Bhamla, an assistant professor in Georgia Tech’s School of Chemical and Biomolecular Engineering who studies ultrafast organisms. “There are many very small invertebrates that can achieve fast movement through unusual structures. We really wanted to understand how these spiders achieve that amazing acceleration.”
In addition to measuring the spider’s speed, the researchers are also looking to understand more about spider silk and how it can be stretched to store such an incredible amount of energy. If they can unravel the secret, the findings could influence how tiny robots are powered, they say.
“Unlike frogs, crickets, or grasshoppers, the slingshot spider is not relying on its muscles to jump really quickly,” said Bhamla. “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.”
Dining With Dynes
Not only did the research team decode the spider’s incredible speed, but they believe they also solved another puzzle. The spider does its hunting at night, often in pitch blackness. So the scientists concluded that the spider must use hearing to locate its prey. To test their theory, they used a very non-scientific approach. They snapped, and the spiders launched.
The study thus far has been published in the peer-reviewed journal Current Biology, but the researchers say there is more work to do. They are curious to find out exactly how the spider can hold on to the tension line for extended periods, being that it can take at least 200 dynes to pull the web back and hold it.
“Generating 200 dynes would produce tremendous forces on the tiny legs of the spider,” Bhamla said. “If the reward is a mosquito at the end of three hours, is that worth it? We think the spider must be using some trick to lock its muscles like a latch, so it doesn’t need to consume energy while waiting for hours.”