A type of spider uses its web as a slingshot or a crossbow to catch prey more aggressively.
The triangle-weaver spider, or Hyptiotes cavatus, is capable of winding its own web with elastic energy that when released, it catapults itself into the air to catch an unsuspecting target.
Researchers from the University of Akron in Ohio observed the spiders under lab conditions using high-speed cameras to understand the arachnids' unusual way of using their webs to catch prey.
Triangle-Weaver Spiders' Impressive Web Catapult
In a study published in the Proceedings of the National Academy of Sciences, the researchers explained how the triangle-weaver spiders create their traps. The arachnid first constructs a triangle-shaped web and, using a single string, tightens it by pulling it backward and storing elastic energy. The spider coils the string between its legs and waits for prey to fall into the web.
"When it senses prey hitting the web it releases its legs from the back line," shared Sarah Han, a biologist and the lead author of the study. "And this causes the spider and the web to spring forward with that release of energy, as if you had released that rubber band. ... This causes oscillations in the web that start to entangle the prey."
The researchers also revealed that the spider would use the same technique over and over again so that prey gets more entangled in the web and trapped. It also allows the spider to attack from afar.
The video footages from high-speed cameras revealed that the webs store a staggering amount of energy. When released, the web reaches an acceleration of about 770 meters a second squared or the equivalent of 400 body lengths in a second.
Power Amplifications Using Tools
The process is called "power amplification" and the team believes that this is the only known example in the animal kingdom that uses an outside object to store and increase energy to be released all at once.
The team also used computer models to run simulations of the spider using power amplification from its web. They compared it to simulations of the spider using muscle power alone and using internal energy alone.
They confirmed that the energy stored and increased in the tension-loaded web allows the spider to catch prey.