The beady bits on the front of the Pacific barreleye fish in this picture released February 23, 2009, aren’t eyes but smell organs.
The grayish, barrel-like eyes are beneath the green domes, which may filter light. In this picture the eyes are pointing upward–the better to see prey above in the darkness of the barreleye’s deep-sea home.
Since the eyes are upright tubes, “it just looked like [they only] looked straight up,” MBARI marine technician Kim Reisenbichler said. But by watching live fish from a remotely operated vehicle (ROV) and by bringing a barreleye to an aquarium for study, the scientists discovered that the eyes can pivot, like a birdwatcher pointing binoculars.