JUMPING SPIDER

The 'jumping spider' 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 (Peng ''et al.'', 2002). 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).

Contents

Habitat

Appearance

Behavior

Vision

Diet

Hunting

Nectar

Gliding

Venom

Reproduction

Gallery

See also

References

External links

Habitat

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 (Wanless, 1975). Certain species of Salticidae are quite common in Europe, such as the Zebra Jumping Spider ''Salticus scenicus'', which is commonly found resting on sun-warmed stone or brick walls.

Appearance

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.

Behavior

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 spiders to jump without having large muscular legs like a grasshopper. The jumping spider can therefore jump 20 to 60 or even 80 times the length of their body. When a jumping spider is moving from place to place, and especially just before it jumps, 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. Minute hairs and claws on their feet enable them to grip imperfections in the glass.
Jumping spiders also use their silk to weave small tent-like dwellings where females can protect their eggs, and which also serve as a shelter while moulting.
Jumping spiders are known for their curiosity. If approached by a human hand, instead of scuttling away to safety as most spiders do, the jumping spider will usually leap and turn to face the hand. Further approach may result in the spider jumping backwards while still eyeing the hand. The tiny creature will even raise its forelimbs and "hold its ground." Because of this contrast to other arachnids, the jumping spider is regarded as inquisitive as it is interested in whatever approaches it.

Vision

Jumping spiders have very good vision centered in their median eyes (AME). Their eyes are able to create a focused image on the retina, which has up to four layers of receptor cells in it (Harland & Jackson, 2000). Physiological experiments have shown that they may have up to four different kinds of receptor cells, with different absorption spectra, giving them the possibility of up to tetrachromatic color vision, with sensitivity extending into the ultra-violet range. It seems that all salticids, regardless of whether they have two, three or four kinds of color receptors, are highly sensitive to UV light (Peaslee & Wilson, 1989). Some species (for example, ''Cosmophasis umbratica'') are highly dimorphic in the UV spectrum, suggesting a role in sexual signaling (Lim & Li, 2005). Color discrimination has been demonstrated in behavioral experiments.
The principal eyes have high resolution (11 min. visual angle) [1], but the field of vision is narrow, from 2-5 degrees.
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.[2]

Diet

Hunting

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 many 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.

Nectar

Even if there are no spiders that are pure herbivores, there are some jumping spiders which include nectar in their diet (Jackson ''et al.'', 2001). 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.

Gliding

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.

Venom

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.

Reproduction

Jumping spiders use 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.

Gallery

See also

★ List of Salticidae genera - List of Salticidae species

★ Spider families

References

★ (1953). ''How to Know the Spiders'', Dubuque, Iowa.

★ (1954). ''The Life of the Spider''. Mentor.

★ (1975). Spiders of the family Salticidae from the upper slopes of Everest and Makalu. ''Bull. Br. arachnol. Soc.'' '3': 132-136.

★ (1982). Vision and prey-catching strategies in jumping spiders. ''American Scientist'' '70': 165-175.

★ (1982). The behavior of communicating in jumping spiders (Salticidae). In P. Witt and J. Rovner (eds).''Spider Communication Mechanisms and Ecological Significance'', p. 213-247. Princeton, New Jersey.

★ (1989). Spectral sensitivity in jumping spiders (Araneae, Salticidae). ''Journal of Comparative Physiology A'' '164': 359-363.

★ (1992). A review of the ethology of jumping spiders (Araneae, Salticidae). ''Bulletin of the British Arachnological Society, 9''33-37.

★ J (1997). ''A Field Guide to Spiders & Scorpions of Texas''. Gulf Publishing Company. Houston, Texas. p.127.

★ (2000). 'Eight-legged cats' and how they see - a review of recent research on jumping spiders (Araneae: Salticidae). ''Cimbebasia'' '16': 231-240 PDF

★ (2000). Learning and discrimination of colored papers in jumping spiders (Araneae, Salticidae). ''Journal of Comparative Physiology A'' '186': 897-201.

★ (2001). Jumping spiders (Araneae: Salticidae) that feed on nectar. ''J. Zool. Lond.'' '255': 25-29. PDF

★ (2002). Five New and Four Newly Recorded Species of Jumping Spiders from Taiwan (Araneae: Salticidae). ''Zoological Studies'' '41'(1): 1-12.
PDF

★ (2003). Seismic signals in a courting male jumping spider (Araneae: Salticidae). ''Journal of Experimental Biology'' '206': 4029-4039.

★ (2005). Extreme ultraviolet sexual dimorphism in jumping spiders (Araneae: Salticidae). ''Biological Journal of the Linnean Society'' '89': 397-406.

★ (2005). Salticidae. pp.205-216 ''in'' D. Ubick, P. Paquin, P. E. Cushing, and V. Roth (eds.) ''Spiders of North America: an identification manual.'' American Arachnological Society.

External links

★ Global Species Database of Salticidae

★ Video of a jumping spider's mating behavior

★ World Spider Catalog

★ Bimodal breathing in jumping spiders: morphometric partitioning of the lungs and tracheae in Salticus scenicus (Arachnida, Araneae, Salticidae).

★ Jumping Spiders of the World

★ Jumping Spiders of NW-Europe

★ Jumping spiders of Australia

★ Jumping spiders of Wisconsin

★ Generic key to the West-African salticid genera (PDF, Hungarian/English)

★ Movies of ''Habronattus'' courtship behavior

★ Male jumping spider courtship dance with contact microphone picking up and amplifying sounds