Spider’s Jump Stabilized By Silken Line

Human jumpers are pretty pathetic when compared to jumping spiders. These arachnids can hurdle themselves to destinations of various heights and cover distances up to 25 times their own body length. That’s like a six-foot-tall man jumping 150 feet, starting from a standstill.

Most jumping spiders attach a silk dragline to their starting point, which was thought to be a safety line. That line has a second purpose, researchers have just found — stabilization. They report their findings in the Journal of the Royal Society Interface.

The team of researchers from Taiwan captured 27 Adanson’s house jumpers (Hasarius adansoni) near Taichung City. Twenty-two of the spiders deployed silk when they jumped, and five did not. The five that didn’t use silk ended up being natural controls in a jumping test, letting the researchers compare jumps with and without silk. The scientists had each of the spiders leap three times, filming them with hi-speed cameras (see video above for an example of a jump).

Spiders that used a dragline had a stable body position in the air and a smooth landing. Those that didn’t, however, pitched rearward in the air and landed more upright, falling forward and slipping or tumbling as they made contact with the ground.

“These results suggest that dragline silk can function as a body stabilizer to prepare salticids [jumping spiders] for a predictable, optimal landing posture,” the researchers write, “and hence is critical for these agile and efficient hunters.”

Video from Kai-Chung Chi et al.