texified

     I came across a reference to camel eyes while reading a work by David King (Skeletons on the Zahara), who wrote about the crew of an American ship who were shipwrecked on the African Sahara in the early nineteenth century.   Since the eyelid is very thin, the camel often closes this eyelid in sandstorms and keeps on walking since he can still see through it.  Camels also have long eyelashes that help protect the eyes from the sand.  Their feet are also broadened (often as large as a large plate) to walk up on sand with out sinking into it.  Planet pets gives a great illustration of the third eyelid of camels that act like a windshield wiper on a car and wipes the sand away. 

     There are other mammals that have this so-called nictitating membrane.  The full membrane is common in Marsupials and Monotremes, but is also found in polar bears, seals and aardvarks.  In most other mammals there is just a remnant of the membrane.  The full membrane is also found in fish, amphibians, reptiles and birds.

    I remember as a child noticing this membrane while trying out some interesting experiments with chickens.  I heard that if a chicken had its beak held down to a line on the ground (or a rope), it would stay in position when released as if paralyzed.  Also if its head was pushed up under its wing it would remain motionless on the ground if released.  The latter is true, although I never really was able to test the line hypothesis very well. 

    While holding the chicken I noticed that its ear appeared to be a simple hole in its head covered by a small flap of bristly feathers.  When I rubbed this flap of feathers, the nictating membrane of the chicken would immediately close over the chicken’s eye and it seemed to go into an estatic trance.  Or at least it seemed a trance to me, because I could set the chicken down on the ground and it wouldn’t run away, but would sit there in a somewhat befuddled state.  This was my first time that I noticed the nictitating membrane.

       I later found out that although chickens have no real outer ear or pinna, they do have a type of ear lobe.  Also you can predict the color of their eggs from the color of this ear lobe.   I found this hard to accept actually.

     They think that the same gene that controls the lobe color also controls the egg color.  Their ear lobes typically run from white to near black, whereas the corresponding egg color ranges from white to a deep brown in conjunction with the lobe color.

     Chickens are curious creatures, I have always thought.