A part of it is completely transparent

Feb 24, 2009 08:19 GMT  ·  By

The Macropinna microstoma, a type of barreleye fish, has to be one of the most amazing creatures to have ever existed on the face of the Earth. Accustomed to living in the pitch black of the deep seas, the animal developed an unique and very useful ability – to see through its own head. During the evolution of the Macropinna, nature decided at some point that the top of the fish's head be transparent and that its eyes receive the ability to move themselves inside the head.

Thus, our eyes are now charmed at the sight of a fish that can literally look through itself. Viewed from the front, the creature appears to be just like the average fish, but the differences immediately become clear when looking at it from the side or from the top. While its body is mostly dark, the top part of its head is transparent, and its eyes can be clearly seen. Thus far, scientists have thought that barreleye fish could only look upwards, but they have recently learned that the creature can also look forward, so as to align its mouth with its eyes.

According to evolutionary biologists, it developed such a powerful sense of sight on account of the harsh environment it lives in. Basically, what the fish does is sink to great depths, just below the line down to which sunlight can penetrate the water. This means that creatures around it cannot see it very clearly. Predators looming above cannot spot it either, but it can look upwards, to hunt for the small fishes and plankton it feeds with. When a suitable target is identified, it attacks out of the darkness, and swiftly engulfs its prey.

To avoid looking at the Sun when it moves out of the deep seas and towards the surface, the creature's eyes can rotate to look forward, thus making it bearable for it to swim and actually see where it's going. As far as appearance goes, its eyes glow a very bright green and researchers believe that the animal has developed a light filter of sorts, which allows it to ignore the sunlight and spot the bioluminescence of small fish and jellyfish, its favorite meals.

Over the eyes, its head is filled with some sort of crystal clear liquid, held together by a tiny membrane. If that were to crack, its eyes would become exposed to the sea, and the pressure that exists at depths of 2,000 to 2,600 feet (600 to 800 meters) would instantly kill the creature. While it's only a few inches long, the barreleye fish is certainly one of the most surprising beings on the planet.