How Many Eyelids Does a Camel Have?
A camel’s large, dark eyes are protected by three eyelids. The two outer eyelids have long, thick eyelashes that protect the eyes from swirling sand. A thin inner eyelid winks over the eyeball and wipes off any dust that may get in. Thick eyebrows shade the eyes from the glare of the desert sun.
The camel’s nostrils are slanting slits that can be closed tightly, serving as additional protection against the blowing sand. The camel’s ears are covered with hair, even on the inside. The hair helps to keep out sand or dust that might blow into the camel’s ears.
The nictitating membrane often called a third eyelid or haw, it may be referred to in scientific terminology as the plica semilunaris, membrana nictitans or palpebra tertia is a transparent or translucent third eyelid present in some animals that can be drawn across the eye for protection and to moisten it while maintaining visibility.
Some reptiles, birds, and sharks have full nictitating membranes; in many mammals, a small, vestigial portion of the membrane remains in the corner of the eye. Some mammals, such as camels, polar bears, seals and aardvarks, have full nictitating membranes.