nictitate

Separately, the sclera, the eye’s outer layer, would most closely resemble those of horses and cows and include a nictitating membrane, the built-in goggles that make it possible to see underwater.

In her 2018 special “Elder Millennial,” she references a nictitating membrane, the translucent inner eyelid typically found in reptiles and birds.

A thin nictitating membrane covers their eyes to protect against sandstorms, and bushy eyebrows and a double row of extra-long lashes help to keep sand out.

A cat has upper and lower eyelids that meet when the eye closes, along with a mysterious third eyelid—more properly called the palpebra tertia, also known as the nictitating membrane or “haw.”

He heard the eyases chittering, saw Frightful sitting erect on her stub, and let his nictitating membranes slip across each eye.