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These videos are easy to view. Just use a program that can display MPEG-1 video. On a PC you can use MEDIA PLAYER which comes with all versions of Windows. On a Mac you can use SPARKLE (download it from here).
DON'T MISS THE MONTHLY CROC SHOTS!
PIC OF THE MONTH
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| DESCRIPTION |
SIZE |
DURATION |
DOWNLOAD |
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EYE OPEN 1
(C. porosus) |
229 kb |
4 secs |
MPEG-1 |
 This video shows an Australian saltwater crocodile (sub-adult) opening its eye. What makes it particularly interesting is the nictitating membrane, or third eyelid, which sweeps across the eye as it opens. You'll notice that the nictitating membrane is transparent except for the leading edge which is pigmented and contains some cartilage. This membrane has two main functions: firstly, it cleans and lubricates the eye, with the help of fluid secreted from the lacrymal (tear) duct - yes, crocodiles do have tears; secondly, it is used when the crocodile dives underwater. Although nobody is quite sure how well the crocodile can see underwater, the transparent membrane which covers the eye during diving ensures that light can reach the eye if the water is clear enough to see. It is possible that the membrane itself alters the refractive index of light entering the eye to possibly improve vision underwater slightly.
One final thing to notice: it is the lower eyelid which moves when the eye opens and closes, contrary to the incorrect information you'll find in a few crocodile text books!
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