Coldwaterjohn's photos with the keyword: Nictitating Membrane

Greater Spotted woodpecker's "third" eyelid

Greater Spotted woodpecker's "third" eyelid

Coldwaterjohn
11 Sep 2017 101
The nictitating membrane (from Latin nictare, to blink) is a transparent or translucent third eyelid present in woodpeckers that can be drawn across the eye from the medial canthus for protection and to moisten it while maintaining vision.