2006-08-30 15:54:05 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Biology
Because of the tapetum (mirror-like thing) in the back of their eye that helps them see in the dark better.
2006-08-30 15:57:45 · answer #1 · answered by Anonymous · 1⤊ 0⤋
It is is indeed the tapedum lucidum as previously said. They actually don't glow at least not very much. They look like they are glowing but they are actually reflecting. Glowing implies it is giving off light. On a related topic that I thought was interesting, humans have a membrane just like the tapetum lucidum behind the retina at the back of the eye that absorbs light. The reason for this is that if light reflected back it would result in a slightly blurrier vision. Human ancestors apparently needed to have very keen day vision. It was apparently more important to gain visual acuity than too retain the enhanced night vision.
2006-08-30 17:39:07 · answer #2 · answered by JimZ 7 · 0⤊ 0⤋
Mammals evolved very early during the time of the first dinosaurs, and they were only just barely able to escape extinction by becoming very small very fertile very nocternal creatures. Seeing in the dark was essential to their survival, and so they lost the ability to see colors which is fairly useless in the dark and instead developed many excellent adaptations for night vision. One of these was a mirror like layer of cells that bounces the light signal through the retina twice, once incoming and again outgoing, essentially doubling the light sensing capability. After the fall of the dinosaurs, we primates came out of the nightlife and began living in the trees, causing us to lose the mirror, (but we re-invented color vision, which most mammals lack to this day.) Unlike us, most mammals have retained the mirror in the back of their retinas, including dogs, making them easy to spot if you shine a flashlight at them at night. I read that this is one of the best ways to find out if a leopard or tiger or the like is stalking you in the night jungle. Their eyes are a dead givaway to anyone armed with a flashlight.
2006-08-30 16:13:19 · answer #3 · answered by Sciencenut 7 · 0⤊ 0⤋
Yeah. Tapetum, that's what it is...
It's this thin layer of reflective cells on the back side of the eyeball. It catches the light, reflects it back out the eyeball, and provides a tiny bit more light to see by at night. Lots of nocturnal animals have them. Dogs, cats, sharks...
Very reflective stuff that tapetum is, a lot like bike reflectors.
2006-08-30 16:02:05 · answer #4 · answered by ye_river_xiv 6 · 0⤊ 0⤋
Because of their tapetum lucidum. It's a reflective surface behind the orbits that allows some animals to see better at night. Most nocturnal mammals have this.
2006-08-30 17:03:12 · answer #5 · answered by DikkiJones 3 · 0⤊ 0⤋
I think its the reaction to the light. Causing its eyes to glow according to the type of light particles being shone on the dogs' eyes' pupils.
2006-08-30 16:00:52 · answer #6 · answered by cheddarc2020 2 · 0⤊ 0⤋
rent the movie cujo to find out the answer.
2006-08-30 16:10:54 · answer #7 · answered by Anonymous · 0⤊ 0⤋
light reflecting off their retinas
2006-08-30 16:01:05 · answer #8 · answered by Mopar Muscle Gal 7 · 0⤊ 0⤋
that is their nightvision working
2006-08-30 15:59:50 · answer #9 · answered by boomboom28655 2 · 0⤊ 0⤋