Montana Public Radio

Bug Bytes: Jumping Spiders

Jun 12, 2020

Of all the different kinds of insects and arthropods we encounter, on average, people tend to be most afraid of spiders. But with their big eyes and fuzzy little bodies, jumping spiders are the cute puppy dogs of the spider world.

If you’ve ever watched one of these spiders, it becomes obvious how they received their name…they jump. Some species can leap up to 50 times their own body length. In comparison, from a standing start, humans can only jump about one and a half body lengths (at best).The act of jumping has nothing to do with muscles or the size of their legs. Their impressive abilities come from an internal hydraulic system -- or the pressure of fluids within their exoskeleton.

A phidippus johnsoni, more commonly known as a Johnson jumping spider.
Credit Glenn Marangelo

So when a jumping spider wants to spring into action, they contract special muscles to increase the flow of blood to their legs. Their body acts like a fluid-filled bellows, pushing blood to the legs in a fraction of a second and sending the spider flying.

While jumping spiders are active hunters, springing upon and tackling their prey rather than using a web for capture, they are anything but reckless. Before launching upon a potential meal or hopping to a different leaf or branch, they will attach a safety line before they jump – catching them in case they fall.

After all…safety first. Because if a jumper, or any spider, were to puncture or crack their exoskeleton or lose a leg, they risk losing their hydraulic pressure, literally deflating and impacting their ability to move.

Jumping spiders’ incredible ability to leap, coupled with what is thought to be the best vision in the spider world, make these cute little spiders extremely capable predators.