The fish gets its name from its eyes that are shaped like barrels. The eyes have beautiful green lenses as you can see in the photo. Perhaps their most interesting feature is the dome of their head; it is completely transparent. This transparent dome was never seen until 2004, because it bursts when it is brought up to the lower pressures near the surface of the ocean.
The barreleye fish like to hunt just below the boundary between light and dark. The ocean is a very dark place below 200 meters. Their eyes are super sensitive and from the darkness they can look up and see the silhouettes of their prey. It is a very unique adaptation.
Find more information about the barreleye in the links listed below.