Nictitating membranes act as a type of third eyelid going horizontally across the eye and found in some animals like birds, reptiles and some mammals.

Nictitating membranes act as a type of third eyelid going horizontally across the eye and found in some animals like birds, reptiles and some mammals.

Nictitating membranes act as a type of third eyelid going horizontally across the eye and found in some animals like birds, reptiles and some mammals.

Members of the genus Somniosus, like the Pacific sleeper shark, lack a nictitating membrane on the eye.

But when the shark was about a few inches from the ray, the shark rolled its nictitating membrane – also known as the third eyelid for shielding the eye from debris, dust and injury – and ...

Fetal Membranes The fetal membranes consist of the chorion, amnion, yolk sac, and allantois. The chorion has three layers: cytotrophoblastic, chorionic connective tissue, and basement membrane.