Spookfish

Spookfish

Spookfish, any of about eleven species of small fishes in the family Opisthoproctidae (order Salmoniformes), can be found in each of the major oceans. The name spookfish is often given the name Barreleyes, because of the unusual evolutionary trait that these fish have developed where their eyes are pointed upwards and are large and tubular. These fish appear to have four eyes, but in actuality they only have two, each of which is split into two connected parts. Their eyes are designed in this way because spookfish are usually found at least 100 meters below the surface, though some specimens have been found at depths of almost 900 meters. The faint light at such depths has forced the spookfish to develop such unique eyes, where one half points upwards to capture the faint glimmers of light from the surface, while the other half point downwards. Not only are their eyes split, but they use a mirror to form an image. The mirror uses tiny plates arranged into a multi-layer stack in order to reflect what little light there is at such depths into the fish's retina. 

http://news.bbc.co.uk/2/hi/7815540.stm
http://oceana.org/en/explore/marine-wildlife/pacific-spookfish
http://www.britannica.com/EBchecked/topic/560885/spookfish