Its vertical orientation is of significance too, as it works well with eyelids. As an animal squints, partially closing its lids at right angles to the vertical slit pupil, it further reduces the amount of light entering its eye. Perhaps the most noteworthy of all pupils is the stenopeic pupil of the gecko, a vertical slit lined with notches on each margin. When the pupil is entirely closed, tiny pinholes allow light to pass through to the retina creating sharp overlapping images. This material may be copied for use in student classroom projects and reports.
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