The jumping spider family (Salticidae) contains more than 500 described genera and about 5,000 described species, making it the largest family of spiders with about 13% of all species.
Jumping spiders have some of the best vision among arthropods and use it in courtship, hunting, and navigation. Though they normally move quietly and fairly slowly, most species are capable of very agile jumps, notably when hunting, but sometimes in response to sudden threats. Both their book lungs and the tracheal system are well-developed, and they use both systems (bimodal breathing). Jumping spiders are generally recognized by their eye pattern. All jumping spiders have four pairs of eyes with one pair being their particularly large anterior median eyes.
Jumping spiders are generally diurnal, active hunters. Their well-developed internal hydraulic system extends their limbs by altering the pressure of body fluid (hemolymph) within them. This enables the spiders to jump without having large muscular legs like a grasshopper. Most jumping spiders can jump several times the length of their bodies. When a jumping spider is moving from place to place, and especially just before it jumps, it tethers a filament of silk (or ‘dragline’) to whatever it is standing on to protect itself if the jump should fail. Should it fall, for example if the prey shakes it off, it climbs back up the silk tether. Some species, such as Portia, will actually let themselves down to attack prey such as a web spider apparently secure in the middle of its web. Like many other spiders that leave practically continuous silk trails, jumping spiders impregnate the silk line with pheromones that play a role in social and reproductive communication, and possibly in navigation.
Certain species of jumping spiders have been shown by experiment to be capable of learning, recognizing, and remembering colors, and adapting their hunting behavior accordingly.