The down-rolled eye we see in so many pictures is evidence that a fish is still neurologically intact. It happens because the brain is still trying to maintain the eye's natural position in space... by that I mean the top stays on top and the bottom stays on the bottom. All vertebrate eyes do this, including yours.

If you are having a conversation with a friend, and tilt your head back into a chin-up position, your eyes will naturally roll downward to maintain their position in space (ie looking at your friend). If you tilt your head to the left (like in Lund's pic in the new STS article) your eyes automatically tilt to the right in an attempt to keep the 12:00 meridian of the eye at 12:00 in space.

The same thing happens to a fish when you pose it for a pic. If the fish is maintained in a natural position in space( held perfectly horizontal, back up, belly down) then the eye will be looking straight out to the side, just like on a free-swimming fish. That straight-out stare does NOT mean it's dead. The best clue you have in this instance is that the pupil will still be very large and shaped like a big fat watermelon seed.

If however you tilt that fish off axis ( e.g. rolling the belly slightly toward the camera to accentuate the chrome snowbelly effect for the final pic) then the eye closest to the camera will appear to roll downward. It is simply trying to maintain its position in space. The opposite eye will actually be rolled upward by an identical amount. A little off-axis tilt, a bit of down-rolled eye... the greater the off-axis tilt, the more the eye rolls down.

If you take your pic with the fish laying completely on its side in the shallows, the down-rolled eye is VERY exaggerated. That's because the body is angled 90 degrees off its normal anatomical orientation. The eye will try to roll downward 90 degrees to compensate for the unnatural body position, appearing partially buried into the socket. If you could view the eye closest to the gravel, you would see that it is rolled upward in an equally exaggerated fashion. Again, the brain is just trying to keep the eyes oriented in space.


Make sense?