Jumping spiders are a diverse group of arachnids known for their keen eyesight and remarkable leaping abilities. These active predators often lead people to wonder about their relationship with silk. Unlike many other spiders, jumping spiders do not construct large, sticky webs to ensnare prey. Instead, they employ a different hunting strategy, relying on their agility and vision.
Hunting Without Webs
Jumping spiders are diurnal hunters. They use their exceptional vision to locate and stalk prey. Their eight eyes, especially the large, forward-facing pair, provide sharp resolution and depth perception, crucial for judging distances. This visual prowess is essential for their hunting technique.
Once a jumping spider spots prey, it slowly stalks, often moving in a zigzag pattern to get closer. When within striking distance, the spider launches itself with a powerful leap, propelled by rapid changes in hydraulic pressure in its legs. They can jump many times their own body length, sometimes up to 40 times. Upon impact, they quickly grab the prey with their front legs and inject venom to immobilize it. This active, visual hunting strategy contrasts sharply with the passive trapping methods of web-building spiders.
The Many Uses of Silk
While jumping spiders do not build webs for capturing food, they are prolific silk producers, utilizing it for various other purposes. One primary use is the dragline, a safety line they trail behind them as they move or jump. This silk tether provides stability during leaps, helps them recover from falls, and allows them to return to their starting point if a jump is unsuccessful. The dragline also stabilizes the spider in mid-air and helps it adjust body orientation for precise landings. This silk is remarkably strong, even surpassing the toughness of some orb-weaver silks.
Jumping spiders also construct silken shelters. These small, enclosed structures serve multiple functions, including resting places, protection during molting, and overwintering sites. Female jumping spiders use silk to create thick, protective egg sacs where they lay and guard their eggs. In some species, silk plays a role in courtship displays, with males incorporating silk to attract females.
Distinguishing Jumping Spiders
Jumping spiders stand apart from many other spider families due to their distinct characteristics and behaviors. Their primary hunting strategy involves active pursuit and pouncing, relying heavily on their superior vision rather than constructing capture webs.
Jumping spiders are more robust and agile in appearance compared to web-builders, and their large, forward-facing eyes give them a unique look. Their active, diurnal lifestyle means they are frequently observed moving and exploring, unlike many sedentary web-dwelling species. This combination of visual hunting, specialized silk uses, and active behavior makes jumping spiders an easily recognizable group within the arachnid world.