2007-01-09 03:00:23 · 13 answers · asked by chrish 1 in Health ➔ General Health Care ➔ First Aid
Most spiders have 8 eyes 2 rows of 4 each, others have 6,4, and 2 eyes. Web building spiders have poor eyesight,spiders that live in caves and other dark areas have no eyesight at all. Spiders eyes are located on top or near the front part of their head.
2007-01-09 03:11:28 · answer #1 · answered by whateverhohum 3 · 0⤊ 0⤋
a spider has 8 eyes
2007-01-10 08:15:32 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Spiders usually have eight eyes in various arrangements. Most species of the Haplogynae have six eyes, although some have eight (Plectreuridae), four (eg., Tetrablemma) or even two (most Caponiidae) eyes. Sometimes one pair of eyes is more well developed than the rest, or even, in some cave species, there are no eyes at all. Several families of hunting spiders, such as jumping spiders and wolf spiders, have fair to excellent vision. The main pair of eyes in jumping spiders even sees in colors.
2007-01-09 21:28:51 · answer #3 · answered by G to eorge 2 · 0⤊ 0⤋
a spider has got 2 eyes
2007-01-09 11:05:48 · answer #4 · answered by masih.nadeem 1 · 0⤊ 1⤋
8
2007-01-09 11:04:29 · answer #5 · answered by bender 3 · 0⤊ 1⤋
8
2007-01-09 11:03:12 · answer #6 · answered by Trublood 2 · 0⤊ 1⤋
Though, i don't see a health related issue here.....it depends on the spider. Some have 4, some 6 and some 8.
2007-01-09 11:03:32 · answer #7 · answered by S H 6 · 0⤊ 1⤋
Spiders usually have eight eyes (some have 6 or fewer), but few have good eyesight. Most are able to detect little more than light-dark intensity changes and rapid movement - enough to stimulate nocturnal web building, hunting or wandering activities, as well as to allow rapid reactions against daytime predators (e.g., by dropping from webs). Some spiders have median eyes that can detect polarised light and they use this ability to navigate while hunting. For most night-active spiders sight is unimportant compared with touch, vibration and taste stimuli.
For a few spiders good vision is vital for hunting and capturing prey and for recognising mates and rivals. They include the day active jumping spiders and flower spiders, and the wolf spiders and net-casting spiders, more often seen by twilight or later at night.
Types of eyes
Eight eyes are typically placed in two rows, on the front of the carapace. The AME or direct eyes, differ markedly in structure from the other indirect eyes (ALE, PLE, PME). The direct eyes appear dark, whereas the indirect eyes usually have a layer of light reflecting crystals, the tapetum, behind the light sensitive retina, giving these eyes a silvery appearance. The tapetum increases visual sensitivity because light entering the light sensitive retinal cells is immediately reflected back through them, so intensifying the image. These indirect eyes are adapted for seeing at low light intensities and their lenses are often enlarged in spiders with good vision. Spider eye lenses are better than photographic lenses in terms of their image brightness (very low F-numbers). However, because most spider eye retinas have relatively coarse-grained mosaics of receptor cells, their resolution of these images is much poorer than in the human eye.
Most wolf spiders hunt in the dimmer light of dusk and moonlight. Their four large posterior eyes have well-developed tapeta which help them spot prey movement in such low light conditions. At night, wolf spiders can be easily spotted because the tapeta in their large eyes shine brightly in torchlight.
2007-01-09 11:08:44 · answer #8 · answered by Basement Bob 6 · 1⤊ 0⤋
Depends on the type of spider, but tarantulas have 8 eyes
2007-01-09 11:04:53 · answer #9 · answered by ammonite132 2 · 0⤊ 1⤋
Depends on the type of the Spider, some have few as four while others have eight.
2007-01-09 11:06:00 · answer #10 · answered by skynickie 2 · 0⤊ 1⤋