page_title: Portia schultzi
section_title: Senses
hierarchical_section_title: Portia schultzi / Senses
caption_attribution_description: English: Jumping spider eyes layout, showing tube for main eyes. Ref: Harland, D.P., and Jackson, R.R. (2000). ""Eight-legged cats" and how they see - a review of recent research on jumping spiders (Araneae: Salticidae)" (PDF). Cimbebasia 16: 231–240. Retrieved on 5 May 2011.
context_page_description: Portia schultzi is a jumping spider which ranges from South Africa in the south to Kenya in the north, and also is found in West Africa and Madagascar. In this species, which is slightly smaller than some other species of the genus Portia, the bodies of females are 5 to 7 mm long, while those of males are 4 to 6 mm long. The carapaces of both sexes are orange-brown with dark brown mottling, and covered with dark brown and whitish hairs lying over the surface. Males have white tufts on their thoraces and a broad white band above the bases of the legs,
  and these features are less conspicuous in females. Both sexes have tufts of orange to dark orange above the eyes, which are fringed with pale orange hairs. Males' abdomens are yellow-orange to orange-brown with blackish mottling, and on the upper sides are black and light orange hairs, and nine white tufts. Those of females are pale yellow and have black markings with scattered white and orange-brown hairs on the upper side. P. schultzi has relatively longer legs than other Portia, and a "lolloping" gait.
context_section_description: Although other spiders can also jump, salticids including P. schultzi have significantly better vision than other spiders, and their main eyes are more acute in daylight than a cat's and 10 times more acute than a dragonfly's. Jumping spiders have eight eyes, the two large ones in the center-and-front position (the anteriomedian eyes, also called "principal eyes") housed in tubes in the head and  providing acute vision. The other six are secondary eyes, positioned along the sides of the carapace and acting mainly as movement detectors. In most jumping spiders, the middle pair of secondary eyes is very small and has no known function, but those of Portia are relatively large, and function as well as those of the other secondary eyes. Jumping spiders' main eyes can see from red to ultraviolet.
  In most jumping spiders, the main eyes focus accurately on an object up to about 75 cm away. However, P. schultzi does not react at all to objectives when the light is under 100 lux. Between 100 and 500 lux, it detects and approaches the objective from distances up to 6 cm, from 500 lux to 1500 lux, its response distance increases gradually to a maximum of about 10 cm, and stronger light causes no increase in the response distance. For comparison, Trite auricoma swivels towards a movement up to 75 cm away and approaches targets from about 20 cm. Perhaps P. schultzi gains little from being alerted to objectives at distances because this spider moves so slowly that it is very unlikely to reach a more distant target in time to catch it.
  Like all jumping spiders, P. schultzi can take in only a small visual field at one time, as the most acute part of a main eye can see all of a circle up to 12 millimeters wide at 20 centimeters away, or up to 18 millimeters wide at 30 centimeters away. A Portia spider takes a relatively long time to see objects, possibly because getting a good image out of such tiny eyes is a complex process and needs a lot of scanning. This makes a Portia vulnerable to much larger predators such as birds, frogs, and mantises, which it often cannot identify because of the other predator's size.
  Spiders, like other arthropods, have sensors, often modified setae (bristles), for smell, taste, touch and vibration protruding through their cuticle ("skin"). Unlike insects, spiders and other chelicerates do not have antennae. A Portia can sense vibrations from surfaces, and use these for mating and for hunting other spiders in total darkness. It can use air- and surface "smells" to detect prey which it often meets, to identify members of the same species, to recognise familiar members, and to determine the sex of other member of the same species.
caption: "Squared-off" cephalothorax and eye pattern of jumping spiders
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