The Creature With a Transparent Head and Tubular Eyes

The Barreleye Fish

Macropinna microstoma has been known since 1939, but a live specimen had not been sighted or caught until 2004. The 6-inch fish lives in deep ocean water, where it ingests mostly jellyfish. The fish's head is a transparent liquid-filled dome. Look at the accompanying photo: Do you see those two eyes above the small mouth? Well, those are not eyes; those are olfactory organs called "nares." In other words, it has two nostrils where the eyes are expected to be. So where are its eyes? Do you see those two green leaf-like structures inside the head? Those are actually eyes, atop tube-like appendages that can move to almost any angle. The eyes are therefore protected inside the head from the stinging jellyfish -- which then explains the advantage of having a see-through noggin.