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  • Zoology

Nictitating membrane

A nictitating membrane is a semi-transparent membrane that may cover the eyes of birds and reptiles in order to moderate the effects of strong light or protect the eye surface from dust particles, etc.

Magpie eye © Gaston Gast - All rights reserved.
Magpie eye
© Gaston Gast - All rights reserved.

Tawny owl © Gaston Gast - All rights reserved.
Tawny owl
© Gaston Gast - All rights reserved.

The two eyes of the tawny owl, an essentially nocturnal bird of prey (contrary to the little owl, which also hunts at dawn), are subjected to the effects of light, which is why the photo shows the symmetrical appearance of nictitating membranes. Among birds with lateral vision, only the eye located on the side facing the sun will protect itself. This is therefore a second example of the "filter that positions itself" - this time on both eyes at the same time.

Nictitating magpie© Gaston Gast - All rights reserved.
Nictitating magpie
© Gaston Gast - All rights reserved.


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