Question: Why are our pupils black?

Alex Evans answered on 16 Mar 2017:

As far as I know, this is because the pupil absorbs the vast majority of light that hits it into the eye, instead of reflecting it back out.

When someone takes a photo and it looks like you have red pupils, this is because the flash of the camera sends light straight into the eye through the pupil and is reflected directly back out – it appears red because of all the blood vessels at the back of your eye!