How many eyelids do cats have? - briefly
Cats have three eyelids: an upper lid, a lower lid, and a third eyelid called the nictitating membrane, which helps protect and moisten the eye.
How many eyelids do cats have? - in detail
Cats possess three eyelids, a unique anatomical feature that sets them apart from humans and many other animals. The most prominent eyelid is the upper and lower pair, which function similarly to human eyelids, opening and closing to protect the eye and distribute moisture. However, the third eyelid, known as the nictitating membrane, is a thin, translucent layer located in the inner corner of the eye. This membrane serves multiple purposes, including providing additional protection, removing debris, and maintaining moisture by spreading tears across the cornea. It is particularly active during moments of vulnerability, such as when a cat is sleeping or hunting, as it can slide across the eye without fully obstructing vision. This evolutionary adaptation ensures that cats’ eyes remain healthy and functional in various environments, from dusty terrains to low-light conditions. The presence of the nictitating membrane underscores the remarkable efficiency of feline anatomy, tailored to their active and often predatory lifestyle.