[cdurk5]

well, im not sure if qazibasit meant me or the other chris that responded to my question. All i know about the tapetum lucidum, is that is a living "mirror" that is right behind cat and dogs(for example) retinas i believe, and somehow what they see bounces off of the tapetum lucidum and allows them to see it twice, giving them another chance to use what little light there is. This is one of a couple different definitions i found on the internet, so im not totally sure if its correct.
Chris

[qazibasit]

well definitely cdurk5 i am thanking you.

[chris]

Hi Chris

yep, your description of the tapetum lucidum pretty much hits the nail on the head.

Here's a link to a show we did about why animals eyes glow at night. The answer is in the soundtrack, or in full further down the page.

http://www.thenakedscientists.com/HTML/shows/2003.03.21.htm

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Quantumcat]

quote:Originally posted by Rokitansky

This is a classical physiology question. Generaly, there are three ways of the adaptation on darkness.

1st  Neural adaptation is the fastest, It includes neurons in the optical pathway and in the brain. It`s not very great, it allows the eye to adapt to 2-3X lower degree of lightness.

2nd Changing the diametar ot the eye pupil accounts for up to 30X change in the degree of adaptaton. It`s also fast.

3rd In the dark, quantity of photosensitve pigment in rods and cons is increasing in the absance of light. This can take several minuts for full adaptation, but the degree of it is very high, up to 25 000 X. Cons are being adapted faster then rods, but they adapt to a far less extent then cons.

All three types of adaptation are performed simultaniously.

"Con" means Bastard, ********, Real Idiot, etc in French []
I think you meant "cone"

Here's an experiement to do with the pigment that heightens the activity of your rods:

Get a lightbulb.
Stare at the lightbulb for about 20 - 30 seconds or longer (longer the better)
Turn off lightbulb and close your eyes immediately and put your hands over your eyelids for an even better image.
What do you see?

I learned why that happens in Year 7 but kind of forgotten now. Maybe someone can explain (if they haven't already, haven't read all replies)


Am I dead? Am I alive? I'm both!