From Wild Wings Inc

Screech owls have a built-in third eyelid, called a nictitating membrane, that sweeps diagonally across the eye. It acts like a clear shield, protecting the eye from debris while still allowing the owl to see. This helps them hunt and move through dense branches without losing sight of their surroundings.

All owls have these membranes, to my knowledge. They also help keep the eyes from drying out while flying.

    • anon6789@lemmy.worldOP
      2·
      15 days ago

      Lots of animals do! And what if I told you that you are (kinda sorta) one of them?!

      This little bit is what is thought to be left of ours.

      From Wikipedia:

      Fully developed nictitating membranes are found in fish, amphibians, reptiles, birds and mammals, but are rare in primates. In humans, the plica semilunaris (also known as the semilunar fold) and its associated muscles are homologous to the nictitating membranes seen in some other mammals and other vertebrates. In most primate species, a plica semilunaris is generally not present, although fully developed nictitating membranes can be found in lemurs and lorisoid primates. Some mammals, such as camels, polar bears, seals and aardvarks, have full nictitating membranes, and many mammals retain a small, vestigial portion of the membrane in the corner of the eye.

      • vermeil@feddit.org
        2·
        15 days ago

        Cool. Wish mine were still working - every day I have to fish some lashes out of my eyes.