The jumping spider family (Salticidae) is one of the coolest spiders in the world, in my opinion.
This family of spiders contains about 5,000 species which makes it the largest family of spiders in the world with about 13% of all spider species.
Most of those species are capable of incredible jumps in both hunting and avoiding threats – relative to their minute size. Jumping spiders are generally recognized by their eye pattern, all the jumping spider species have four pairs of eyes.
The jumping spiders, unlike the other families of spiders, have faces that are roughly rectangular surfaces perpendicular to their direction of motion. In effect this means that their forward-looking, anterior eyes are on “flat faces”.
The large anterior eyes of Salticidae are adapted to detailed, three-dimensional vision for purposes of estimating the range, direction, and nature of potential prey, permitting the spider to direct its attacking leaps with great precision. The anterior lateral eyes, though large, are smaller than the AME and provide a wider forward field of vision.
Two theories are offered to account for the retinal layering. Either the spider uses different layers to examine maximally sharp images of objects at different dis tances; or each layer exploits the sharpest image of distant objects, but for light of different wavelengths. Scientist are not exactly sure. Making this species in particular an enigma of sorts.
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 almost 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. They are not stupid that is for sure. In fact they are remarkable creatures!
See video: Phidippus Carolinensis Jumping Spider Being Cute http://www.youtube.com/watch?v=DsGvT2DYJMc
When it detects potential prey, a jumping spider typically begins orienting itself by swivelling its cephalothorax to bring the anterior median eyes to bear. It then moves its abdomen into line with its cephalothorax. After that, it might spend some time inspecting the object of its attention and determining whether a camouflaged or doubtful item of prey is promising, before it starts to stalk slowly forward. When close enough, the spider pauses to attach a “dragline” of silk, then springs onto the prey.
This species of spider are continually on the move, stopping periodically to look around for prey, which they then stalk immediately. They are extraordinary hunters. They are without a doubt the apex predator of their minute worlds. In some cases taking on prey items 5 times their size.
One undergraduate I talked to recently at Arizona State University says that among all spider species the “Jumping spider in particular are some of the most resourceful, intelligent and dynamic hunters of any known species of spider. Making them absolutely unique.”