I just found some interesting info and thought I would share it. Quite some time ago there was a question asked about whether or not diving ducks close their nictitating membranes underwater, and if so, how do they see?
Here's the scoop:
YES. They do.
Apparently they have a clear contact lens-like window in the center of the nictitating membrane which allows them to see clearly underwater. (G.L. Walls, "The Vertebrate Eye and its Adaptive Radiation", 1942) In addition, they have two focal points on the retina - one for seeing in air and one for underwater.
Amazing what one can learn from the internet!
Now I have to go dig out the freshest diving duck in the freezer and take a very close look at its eyes. Knowing what I'm looking for will be a big help.
(... and there are still some who question the value of taxidermy competitions!)
Nancy M.
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Obviously Nancy M. will be competing at the World's with a diving duck underwater which will contain a covered over eye. Don't deduct points - in fact you should give her extra!
I do remember the previous post - wonder how the fellow did on his underwater diving mount.
Its one of those things 99% of the taxidermist would have never known.
The contact lens portion of the nic. mem. is bulged like the fish eye lens of a camera. This allows the duck to see a wide range of view.
Another point to remember is that dirds and fish can see while thier eyes are looking in different directions.
Just like a bass moving its eye in and out of the socket. I have two photos of the same fish seconds apart on the kiwi website.