2006-09-13 06:23:56 · 18 answers · asked by SriPada R 1 in Science & Mathematics ➔ Zoology
The number of eyes varies from one kind of
spider to another. The most common number is
eight. Other kinds may have 6, 4, 2, 1 or 0 eyes.
After 8, 6 and 0 are the commonest numbers.
Only one has ever been found with a single eye
and it may be an abnormality. There are none
known with more than 8, though certain accidents
may make them appear to have more. It is
possible that some error in development might
make one of them actually have more than 8.
A spider's eyes are located on the cephalothorax. Most spiders have 6 or 8 eyes. Spider eyes are considered "simple": they do not have multiple lenses and facets as do the compound eyes found on some insects. Although some spiders can only see the difference between light and shadow, others, especially Jumping Spiders, are believed to have excellent eyesight.
The eyes are located in the front. Most spiders have eight eyes, some 6. But there are spiders with no eyes, 2, 4 and up to even 12 eyes. The eyes are singular and are called ocelli, unlike the insects that have compound eyes. The main pair of eyes is always the middle pair and has a different construction than the other eyes. The light sensitive cells point towards the incoming light and is therefore referred to as indirect retina. Except the crab spiders and jumping spiders, the main eyes are small or even absent in spiders with six eyes. The construction is similar to as in humans and these eyes have a high resolution. In the other eyes the light sensitive points away from the light and have an indirect retina. These secondary eyes give the spider a much broader field of vision than the main eyes and are used to give them the ability to judge distance. During hunting, these secondary eyes catch the movement of the prey and the main eyes are used to focus as it moves closer to the prey.
Have a good day!
2006-09-13 06:32:05 · answer #1 · answered by mbjwithouse 2 · 2⤊ 0⤋
Spider Eyes
2016-12-08 21:54:26 · answer #2 · answered by zabel 4 · 0⤊ 0⤋
2
2006-09-13 06:37:02 · answer #3 · answered by eugene65ca 6 · 0⤊ 0⤋
8
2006-09-14 21:18:34 · answer #4 · answered by Solar Sarab 2 · 0⤊ 0⤋
8
2006-09-14 03:08:26 · answer #5 · answered by Anonymous · 0⤊ 0⤋
8
2006-09-13 07:57:02 · answer #6 · answered by doggcmc 1 · 0⤊ 0⤋
8
2006-09-13 06:25:28 · answer #7 · answered by tina m 6 · 0⤊ 0⤋
8 or 12
2006-09-13 06:44:07 · answer #8 · answered by jannat1812 2 · 0⤊ 0⤋
Most species have eight eyes, arranged in two rows of four each. Other kinds have six, four, or two eyes.
Most spiders have eight eyes, and the way those eyes are arranged can help scientists work out what kind of spider it is.
The two main eyes of a spider each have a simple lens, and a retina which is made up of light sensitive cells whose surfaces point toward he light as it enters the eye. These main eyes have a small field of vision with high resolution. They are especially well developed in jumping spiders. A spider's secondary eyes also have a lens but the light sensitive cells of these eyes point away from the light as do the similar cells in a human eye. The secondary eyes detect shadows and the difference between light and dark.
A spider's eyes are on top and near the front of its head. Different species have different numbers of eyes and the size and position also varies.
2006-09-13 06:25:51 · answer #9 · answered by Anonymous · 1⤊ 0⤋
6
2014-11-12 08:49:21 · answer #10 · answered by lungtum 1 · 0⤊ 0⤋