Day
3A: The Eyes Have It
Look
carefully at these tiny birds. Notice how huge the bulges are where
their eyes are hidden. Bird eyes are ENORMOUS compared to their
heads. Once the eyelids grow in, they will cover all but a small
round part of the eye. Look at a partner's eyes. Our lids open in
an oval-shape. We can see the pupil, iris, and a lot of the white
part. A bird's eyelids open in a round shape. We can only see the
pupil and iris.
Q: Why do human eyelids show more of the eye than a bird's
eyelids show?
(Answer under photo.)
Photo:
Dorothy Edgington
A.
Human eyeballs can turn and roll to see up and down and to both
sides. Our eyelids are shaped as they are so our eyes can still
see when they move side to side. When birds fly, the rush of air
can dry their eyes. To protect them, the lids cover as much of
the eye as possible. Also, bird eyes can't roll like our eyes
do. Because their eyes are much more "fixed" in the
socket, there's no need to have eyelids that allow them to turn
from side to side.
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