Fish with Tubular Eyes and Transparent Head

Researchers recently solved the half-century-old mystery of a fish with tubular eyes and a transparent head.

Ever since the "barreleye" fish Macropinna microstoma was first described in 1939, marine biologists have known that its tubular eyes are very good at collecting light. However, the eyes were believed to be fixed in place and seemed to provide only a "tunnel-vision" view of whatever was directly above the fish's head.

A paper shows that these unusual eyes can rotate within a transparent shield that covers the fish's head. This allows the barreleye to peer up at potential prey or focus forward to see what it is eating.

Below: The Macropinna microstoma has extremely light-sensitive eyes that can rotate within a transparent, fluid-filled shield on its head. The fish's tubular eyes are capped by bright green lenses. The eyes point upward (as shown here) when the fish is looking for food overhead. They point forward when the fish is feeding. The two spots above the fish's mouth are olfactory organs called nares, which are analogous to human nostrils.



Below: In this image, you can see that, although the barreleye is facing downward, its eyes are still looking straight up. This shot shows a barreleye that is about six inches long.



Below: This face-on view of a barreleye shows its transparent shield lit up by the lights of a remotely operated vehicle.



A video is also available from the original article here.