why the eyes of animals shine in dark?
477014
In most mammals, the pupil of the eye is round but in many of the flesh-\neaters such as the domestic cat, it becomes a vertical slit in bright \nsunlight and widens to cover most of the pupil in darkness. That is why \nthey see so well at night. In the eyes of the kangaroo and some hoofed \nanimals, notably the goat, the pupil is a horizontal slit. The eyes of \nmany animals shine at night because of a peculiar mirror, on the retina \nat the back of the eyeball, which reflects light; so that a cat's eyes have a \ngreen glare and those of alligators and crocodiles shine red. Such \neyeshine is found in many other kinds of animals including various \nmammals, sharks, sturgeons, and some moths, but not in birds nor \namphibians: and in all colors except violet and white.\n\nSwift animals, like the antelope, usually have large eyes. Nocturnal \nanimals like the deer mouse and flying squirrel, have also developed \nvery large eyes which enable them to see better and evade their many \nenemies. Others, which live mostly in tunnels, like the meadow mice, \nshrews and moles, have tiny weak eyes. Some, like the earthworm, are \nblind. Land snails have eyes on tentacles with which they can see \naround a corner, but leeches merely have "eye spots " or none at all. \nCrawfish and crabs have eyes on short stalks. Spiders have from 2 to 8 \neyes. Many insects have huge compound eyes -- the dragonfly has from \n20 to 25 thousand tiny lenses in a honeycomb pattern -- and some, like \nthe grasshopper, also have three little "simple" eyes for close vision. \nBirds have the keenest eyes and those of the hawks, eagles and vultures \ncan see small objects at incredible distances.
982294
most people believe that animals don't have they basic intelligence to understand what you might say to them let alone understanding religion.  However since they are cold-blooded, I would say the sun.
824822
They only shine at night. During the day the space gnomes turn them off to save energy.
4964
A rarely good question asked in this section. The color reflected depends on the texture and size of particles in the back surface of the eyes of an animal. Some night vision animals have a better reflecting surface to point any light not captured by the retina back to its light-sensing cells. So light intensity varies, as well as color. The color is not always the same for a certain species in the sense that the color you perceive depends on the angle at which you look at their eyes (you might be able to see the whole spectrum of visible light in some cases).
1080725
shadow is formed through light.
982980
In the eye there r rods N cones. rods allow us to see details while cones colours! cats n dogs have more rods than human beings.
4286
Same reason humans have red eye -> Flash light that is sent directly to the retina (parallel to eye level) is reflected off the blood vessels at the back of the retina, hence the red color.\n\nPerhaps you see it more in dogs and cats because they reflect more light off their retina, thats how they manage to have better eye sight than humans.
663532
the moon passes between the earth and the sun and for a few minutes blots out its light, animals lie down in the fields. thinking nightfall has come
330696
Insects are attracted to the light reflected of the plants and they are most certainly NOT color-blind. Bees can see into the ultra-violet end of the spectrum farther than humans so they don't see the same colors we do.
1155292
COUNTERSHADING is protective camoflauge:\n\nwhite on underside so animals smimming below can't see it as well when blending into sunshine.\n\ndarker color on dorsal side so that animals swimming above it can't see it as well when it blends into darker bottom of pond-lake
175012
Think about it this way.  Have you ever looked at a piece of charcoal lit by sunlight in the middle of the night?  Of course this is impossible, but if you could do it you'd be surprised just how bright it would appear.  In daylight, the charcoal is surrounded by other objects which are better reflectors (higher albedos), making the charcoal appear dark by comparison.
778664
the sun heats up the molecules in the object expanding them slightly usually not noticeable to the human eye, black absorbs the light instead of reflecting it.
1039389
Its dark in your world, isn't it?  :-)
398354
There's a peak absorbance of rods and cones in the retina.  Humans have three peaks which represent the primary colors (for light) red, green, and blue.  The colors we see are our brain's interpretation of input on those three colors plus general light level input from rods.  Based on the numbers of rods and cones and the absorbance spectra of the different cones, researches can get an idea of the color vision of different animals.\n\nMost mammals are dichromatic (two colors).  Note how non-colorful they tend to be.  Certain primates are trichromatic (three colors).  Birds, reptiles, amphibians, and insects are also trichromatic or more.  Note how colorful they tend to be.
572704
Abraham Lincoln was born in a log cabin near Hodgenville, Kentucky\n\nThe luminous appearance of a cat's eyes in the dark is due to the reflection of light by the tapetum lucidum, which is part of the membranous layer between the retina and the outer covering of the pupils of the eyes. This remarkable layer is distinctly differentiated from the choroid layer only in certain animals. It is the tapetum lucidum that enables members of the feline family and other nocturnal animals to see even when there is very little light. Some authorities believe this layer reflects the light rays through the retina a second time. In the domestic cat the tapetum lucidum is brilliant green or blue in color and has a metallic luster. The well known glare is especially noticeable when artificial light is thrown on a cat in a dark corner, or when a cat in a dark place is observed through an opening, light entering the darkness through the opening being reflected from the cat's eyes as from a mirror.\n\n\nShumilikha\n\nMales do not sting
111113
Cats are nocturnal hunters. They have frontally placed eyes that provide good binocular (depth-sensitive) vision. In addition, their eyes are much more sensitive than ours to low light intensities, and they are able to see with very little environmental light (their minimum light detection threshold is up to 7 times less than that of humans). Due to this sensitivity, they could be subject to eye damage during the day, and their vertical pupils could be an adaptation to avoid this. The pupil is the "window" through which light reaches the retina, and a vertical pupil that can contract to a mere slit, in combination with the eyelids that close perpendicularly to this slit, is able to keep excessive light out. In contrast, the cat pupil expands to almost circular shape in the dark. They have other adaptations for night vision (see link).\n\nOther crepuscular/nocturnal animals also have vertical pupils, e.g. many snakes and geckoes.
764385
G'day Alli Oop94,\n\nThank you for your question.\n\nCows can see in things in front of them depending on where they are.\n\nCows are fisheyed with very different eyesight to humans.  There eyesight is poor and they need to lower their heads to see things on the ground. They will baulk at a shadow then lower their head to look at it further. Designers of cattle handling facilities are taking cows poor eyesight into consideration in design.\n\nThey are also colourblind so the legend that bulls get enraged by the colour red is a myth.\n\nI have attached sources for your reference.\n\nRegards