A nictitating membrane is a transparent or translucent membrane that can be drawn across the eye. The only animals that do not have these are primates. Some animals don't have full nictitating membranes. They're also called third eyelids or haws.
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Random biological facts
Non-FictionWhat the title says. Most of these will be about animals and I add these as I think of them. So irregular updates.
Nictitating membranes
A nictitating membrane is a transparent or translucent membrane that can be drawn across the eye. The only animals that do not have these are primates. Some animals don't have full nictitating membranes. They're also called third eyelids or haws.