Jumping Spider (Salticidae) - Wiki
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[Photo] A jumping spider, Phidippus mystaceus female. female Phidippus mystaceus from Austin, Texas. Date 2006-02-21. Author en:User:Dawson http://en.wikipedia.org/wiki/User:Dawson
The jumping spiders (family Salticidae) contains more than 500 described genera and over 5,000 species, making it the largest family of spiders with about 13% of all species. Jumping spiders have good vision and use it for hunting and navigating. They are capable of jumping from place to place, secured by a silk tether. Both their book lungs and the tracheal system are well-developed, as they depend on both systems (bimodal breathing).
Jumping spiders live in a variety of habitats. Tropical forests harbor the most species, but they are also found in temperate forests, scrub lands, deserts, the intertidal zone (in Malaysia), even mountains (one species is reported to have been the spider collected at the highest elevation, on the slopes of Mt. Everest. If this is its natural habitat, then it is probably living as a scavenger, feeding on the insects that are transported up there by the wind and then frozen to death.)
Jumping spiders are generally recognized by their eye pattern. They typically have eight eyes arranged in three or four rows. The front, and most distinctive row is enlarged and forward facing to enable stereoscopic vision. The others are situated back on the cephalothorax.
Colours and patterns vary widely. Several species of jumping spiders appear to mimic ants, beetles, or pseudoscorpions. Others may appear to be parts of grass stems, bumps on twigs, bark, part of a rock or even part of a sand surface.
Jumping spiders are generally diurnal, active hunters. Their well developed internal hydraulic system extends their limbs by altering the pressure of body fluid (blood) within them. This enables the jumping spiders to jump without having large muscular legs like a grasshopper. When a jumping spider is moving from place to place, and especially just before it jumps from one place to another, it tethers a filament of silk to whatever it is standing on. Should it fall for one reason or another, it climbs back up the silk tether.
Unlike almost all other spiders, they can quite easily climb on glass. This is because of the minute hairs and claws found on their feet, which grip minute imperfections in the glass. Jumping spiders also use their silk to weave small tent-like dwellings, where females can protect their eggs and to serve as a shelter while moulting.
Jumping spiders are known for their curiosity. If one approaches a jumping spider and attempts to place one's hand near it, rather than quickly scuttle away in search of cover, the arachnid will more likely than not, jump away and turn to face the hand. Repetition of this action may result in the spider jumping backwards but still eyeing the hand. Because of this contrast to other species, which will sense the hand and run for safety, the jumping spider is regarded as "curious" since the spider is interested in whatever approaches it.
Jumping spiders have very good vision centered in their anterior median eyes (AME). Their eyes are able to create a focused image on the retina, which has four layers of receptor cells in it. Physiological experiments have shown that they may have up to four different kinds of receptor cell, with different absorption spectra, giving them the possibility of up to tetrachromatic color vision, with sensitivity extending into the ultra-violet range. Color discrimination has been demonstrated in behavioral experiments.
Because the retina is the darkest part of the eye and it moves around, one can sometimes look into the eye of a jumping spider and see it changing color. When it is darkest, you are looking into its retina and the spider is looking straight at you.
Jumping spiders capture their prey by jumping on it from several inches away, and they may jump from twig to twig or leaf to leaf. They can jump thirty times their body length. They can carry out complex maneuvers such as detours around obstacles in order to reach their prey. Their eyesight is much better than that of other spiders and most, if not all, insects. Most other spiders will only eat prey that they have captured live because they are unable to see dead prey (some long-legged sac spiders and anyphaenid sac spiders are exceptions as they recognize insect eggs as food) but jumping spiders will eat flies that have been killed for them. One jumping spider (Evarcha culicivora) is even known to only capture mosquitos full of blood, using their eyesight and smell.
Even if there are no spiders that are pure vegetarians, there are some jumping spiders which include nectar in their diet. So far none are known to feed on pollen or seeds. When insects land on plants such as the partridge pea, which offers the spiders nectar through their extrafloral nectaries, the jumping spiders help protect the plant in return by killing and eating insects that might damage the plant.
At least one species of jumping spiders, known as the Gliding Spider (Maratus volans) from Australia, has an abdomen with two wing-like flaps that can be tucked underneath it when not in use. When the spider is leaping, it can use its flaps to extend the jump and glide short distances through the air.
Some jumping spiders may bite to protect themselves if disturbed. However, jumping spiders usually escape and hide, and will only bite if provoked and cornered. While the bite of a larger jumping spider can be painful, only a few species produce any other effects. Almost all spiders (except hackled orb-weavers) have venom, but the venom of most spiders is not worse than the venom of a bee.
Jumping spiders utilize their vision in complex visual courtship displays. Males are often quite different in appearance than females and may have plumose hairs, colored or metallic hairs, front leg fringes, structures on other legs and other, often bizarre, modifications. These are used in visual courtship in which the colored or metallic parts of the body are displayed and complex sideling, vibrational or zigzag movements are performed in a courtship "dance." In recent years it has been discovered that many jumping spiders may have auditory signals as well, with amplified sounds produced by the males sounding like buzzes or drum rolls.
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