Deer have pupils in the shape of a horizontal ellipse to have a horizontal alignment with their environment. When they graze, they turn their eyes 90° clockwise, to keep their view horizontally aligned.
Heads up, looking around, the deer's pupils are horizontal aligned with the horizon
Face down, eating grass, the deer turns his eyes almost 90° to keep his pupils aligned with the horizon
Deer lift their eyebrows to keep their eyelashes horizontally aligned using them as an alignment tool in conjunction with their pupils.
Result: Horizontal alignment defines the way deer control their eyes.
The
purpose of this site is to present questions and new ideas about
the above subjects.