The third eye(lid)

Buy Add to Lightbox
Lucca shows off her third eyelid in this sequence of four photographs taken just after she woke up from a nap.  The third eyelid (nictitating membrane or palpebra tertia) is a thin white membrane that slides horizontally across the eye underneath the outer two eyelids.  Humans lack this third eyelid, but most other vertebrates have it.  Lucca here is simultaneously stretching, yawning, and opening her eyes.  In the first image her eyes are completely closed, in the second image her outer two eyelids are partially open, but the nictitating membrane is still entirely covering the eye, in the third image the outer two eyelids are almost entirely open and the nictitating membrane is about half covering the eye, and in the fourth image all three eyelids are fully open.
Lucca shows off her third eyelid in this sequence of four photographs taken just after she woke up from a nap. The third eyelid (nictitating membrane or palpebra tertia) is a thin white membrane that slides horizontally across the eye underneath the outer two eyelids. Humans lack this third eyelid, but most other vertebrates have it. Lucca here is simultaneously stretching, yawning, and opening her eyes. In the first image her eyes are completely closed, in the second image her outer two...
more »

Copyright

View This Image's Galleries:
Cats - closeups
Keywords:
  • Cat
  • Lucca
  • blue patched tabby and white
  • dilute caliby
  • eye
  • kitties!
  • nictitating membrane
  • palpebra tertia
  • stretch
  • third eyelid