Why do animals get green-eye?

Question

Multiple sources on the internet (including answers on this site) claim that red-eye is created by light from the flash reflecting on the blood vessels in back of the eye.

So, why do animals like dogs, that I believe also have red blood (I'm not going to injure my dog in order to test this, but I'm pretty sure the blood is red) have green-eye?

Maybe some sort of vegetation growing on the back of pet's eyes reflecting the light? — Nir, May 02 '11 at 13:35

score 21 · Accepted Answer · answered May 02 '11 at 14:21

21

Many animals, including cats and dogs, have a reflective layer of cells at the back of the eye called the tapetum lucidum ('the tapestry of clarity'). This reflects the light back through the light-sensitive cells in the retina for a 'second pass', allowing the animal to see better at night.

answered May 02 '11 at 14:21

ElendilTheTall

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You don't have to do photography to notice this green reflective layer; staring into a cat's eye at exactly the right angle will let you see that at naked eye :) – badp May 02 '11 at 18:17
Yup, headlights are particularly effective at showing them up. – ElendilTheTall May 02 '11 at 18:49
Nice answer, +1, but no one as yet has explained why the color is green specifically... – Uticensis May 02 '11 at 20:47
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@billare: actually, eyeshine can be white, green, blue, yellow or pink, depending on the angle you view it at. – ElendilTheTall May 02 '11 at 20:57

score 10 · Answer 2 · edited May 02 '11 at 16:01

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According to Wikipedia it seems that animals that exhibit this phenomenon ("eyeshine") have an extra layer of tissue within their eyes that cause light to be reflected in a different way.

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^{Source: Wikipedia}

edited May 02 '11 at 16:01

Trufa

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answered May 02 '11 at 13:49

Gustav Kores

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Wikipedia has a picture of a cat which dramatically illustrates red eye and "eyeshine" occurring simultaneously. – mattdm May 02 '11 at 14:03

Why do animals get green-eye?

2 Answers2