a membrane that is also known as the haw or third eyelid (nictitating means blinking). It moves horizontally and is most usually seen when a cat is ill or has a foreign body in the eye, and is therefore a cause for concern.
A thin membrane that can be drawn across the eyeball to protect and clean it. Found on many fish species, including some sharks.
The nictitating membrane is sometimes called the third eyelid or the "haw". It is a thin, white membrane that can operate independently of the eyelid. The purpose is to have a form of protection over the eye while still retaining some amount of vision. Note: In the sample graphic, the first image has the nictitating membrane closed while the second image shows the eye not covered by the membrane.
A thin protective membrane (sometimes called the "third eyelid") located at the inner corner of the eye.
a protective fold of skin in the eyes of reptiles and birds and some mammals
in many vertebrates, a membrane of the eye capable of extending over the eyeball.
The bird's "third eyelid;" a semi-transparent membrane that covers the eye while a bird is flying, protecting it from drying out.
The nictitating membrane is the vertical semi-transparent fold under the eyelid. This is also the third eyelid of the bird and can be closed for protection. It has its own moisturizing system similar to tear ducts. It can be closed to protect the parent from their youngling's sharp beaks.
A third eyelid that occurs in birds, reptiles, sharks, amphibians, and some mammals. It is transparent and flicks over the eyeball without shutting out the light.
"third eyelid" drawn over the eye to clean it
Third eyelid, a transparent membrane of birds and many reptiles and mammals, that can be pulled across the eye.
Another name for the third eyelid, the thin membrane that moves across the eye when the upper and lower eyelids are closed, may be visible when a cat is sick
A thin membrane found in many animals beneath the lower eyelid that extends across the eyeball.
A fold of the mucous membrane of the CONJUNCTIVA in many animals. At rest, it is hidden in the medial canthus. It can extend to cover part or all of the cornea to help clean the CORNEA.
Some sharks (Carcharhiniformes) have a nictitating membrane, a type of eyelid that protects the eye during hunting.
Translucent, vertical fold under the eye lid.
A semi-transparent membrane, which can be drawn across the eye in Birds and Reptiles, either to moderate the effects of a strong light or to sweep particles of dust, &c., from the surface of the eye. 133
A transparent inner eyelid in birds, reptiles, and some mammals that closes to protect and moisten the eye. Also called third eyelid.
A thin, tough membrane, or inner eyelid present in the eyes of many sharks. It can be drawn across the eye to protect if it from damage.
The white inner eyelid of some sharks which shuts to protect the eye while fighting and feeding.
Many species of land animals have a nictitating membrane, which can move across the eyeball to give the sensitive eye structures additional protection in particular circumstances. It is often called a third eyelid or haw and may be referred to as the plica semilunaris or palpebra tertia in more advanced applications.
