Salticus scenicus
ORDER
Araneae
FAMILY
Salticidae
TAXONOMY
Salticus scenicus Clerck, 1757.
OTHER COMMON NAMES
English: Zebra jumping spider.
PHYSICAL CHARACTERISTICS
Relatively small- to medium-sized spider, with adult female length of 0.20–0.28 in (5–7 mm) and adult male length of 0.20–0.32 in (5–8 mm). Considered one of most common and well-known salticid spiders. Has very acute vision with distinctive eye arrangement of eight simple eyes (three rows of 4, 2, and 2) that enable it to focus in all directions. First median pair of eyes is largest, located on front of cephalothorax, look forward, and called "headlight" eyes. Posterior eyes are smallest in size, located on top of cehalothorax and look upward. Eyes can move in or out for focusing, and can turn up and
down, and left and right for 360° eyesight (called "integral binocular vision"). Nuclei of retinal cells of anterior eyes have evolved to side, out of the path of light. Can also turn its carapace more than 45° to look around. Considered to have best vision of any arthropod, especially where anterior median eyes are concerned. When eyes become dirty, they are cleaned with front two legs.
Most distinguishing feature is black body that contains white hairs, which form stripes on abdomen. Male is similar to female but with larger chelicerae, darker body color, and brightly colored brushes on appendages. Cephalothorax contains brilliant hairs, stout body, and rather short legs; eight legs are hairy and covered by sensory hairs (trichobothria). Tracheal system extends into cephalothorax. Abdomen contains digestive system, breathing apparatus, and silk-producing organs. Huge chelicerae are usually hidden behind pedipalps.
DISTRIBUTION
Northern Hemisphere, but mostly in northern Europe (and widely distributed throughout England).
HABITAT
Commonly found anywhere outside where sun is shining; especially in gardens, on rocks, stones, flowers, plant foliage, and grass, and occasionally on trees. Often found on vertical surfaces such as walls, fences, decks, patios, and doorways. At night or during rainfall, it hides in dry spots.
BEHAVIOR
Diurnal; most active during hottest days of year, mostly in early to late summer. Often attacks and kills much larger adult hobo spiders, which are competitors for food. Jumps more than it walks. Able to jump from standing start; can also jump backward and sideway with equal abilities. This type of motion is used both to capture prey and to avoid capture by predators. Uses third and/or fourth pair of legs for jumping. Whenever it jumps, it will release thick, white, slightly viscid silky line to use as anchor to crawl back to original position. Silk is produced from special organs (spinnerets) at rear of abdomen. Also produces silken bag ("retreat") in such places as crevices, under stones, under bark, and on foliage and plants. Bags used for protection and shelter at night, resting, molting, feeding, protecting young, and during winter to hibernate.
Prey can be noticed from distance of about 12–16 in (30–40 cm), although it is reported that it can see prey up to 8 ft (2.4m) away. At distance of about 7.9 in (20 cm), it turns its body so that front eyes point to victim; eye muscles focus on prey and the eyes move around optical axis. Able to distinguish between prey and predators, and also capable of distinguishing color. After object is recognized as eatable, it carefully moves toward victim.
FEEDING ECOLOGY AND DIET
Eats primarily insects, but also eats spiders the same size or smaller. It avoids ants. Reported to feed on mosquitoes with lengths almost twice its own. Active hunter, able to catch larger prey primarily because of its excellent eyesight during day (especially in direct sunlight) and excellent ability to jump from a stationary position. Slowly stalks potential prey by creeping very close, usually to within 2.8–5.9 in (7–15 cm). When at reachable distance, it attaches silky thread to substrate, and then jumps on prey and paralyzing it with its venomous jaws. Powerful chelicerae are then used for chewing up prey prior to sucking up liquid contents. Does not make webs for catching prey.
REPRODUCTIVE BIOLOGY
Males court females by dancing and displaying brilliant colors, distinctive marks, and bright appendages. Males deposit sperm on small web to be used as special reservoir within pedipalp to carry seed around. They will then try to mate with females. Mating is dangerous for males, having to convince females that they are prospective mates and not prey. This activity involves various motions with front legs and moving abdomen up and down. (The more they move, the more likely they will be noticed and accepted by female.) During this time, males try to reach reproductive organ of female (epygine), located under abdomen. When sperm is successfully transferred to female, she will carry it in special compartment and use it when she is ready to fertilize eggs. Females lay their eggs in small silky bags mostly in spring and summer for the purpose of being able to protect spiderlings from predators. Females will guard young until they are ready to leave, normally after second molting period. Young usually mature in late spring and summer. Lifecycle is about one year.
CONSERVATION STATUS
Not listed by the IUCN.
SIGNIFICANCE TO HUMANS
Often considered a pest to humans, but it is actually harmless.
