This fish, a Macropinna microstoma, more commonly known as the barrel-eye fish lives off the North Pacific from Bering Sea in the north to Japan and Mexico in the south. They can be found in deep waters. The first thing that struck me about this fish is it’s fluid filled head that is transparent. On top of that, there’s something even more interesting.
If you think you’ve got them…. well, you might be wrong!
The two dark spots above the fish’s mouth is not their eyes. They are actually called nares (something like our human nostrils). Nares are olfactory organs. The fish’s eyes is well inside the head and are capped by bright green lenses. The eyes point upward (as shown in the picture) when the fish is looking for food overhead and the eyes can point forward when the fish is feeding. The eyes are light sensitive and can rotate around in the head.
Because of the layout of their eyes, Barreleyes typically live near the depth where sunlight from the surface fades to complete blackness. The high number of rods in their eyes allow them to resolve the silhouettes of objects overhead in the faintest of ambient light and to accurately distinguish bio luminescent light from ambient light. Their binocular vision allows the fish to accurately track and home in on small preys as well as detect predators. Such optic specializations thus aid in both feeding and predator avoidance.
Hence from this we can see how the eyes structure of the fish actually affect and cause the fish to behave in a certain manner. Their light sensitive eyes allows them to live deep in the waters where there is little or no sunlight. Their eyes position also help in them obtaining food for survival. People may think that barreleye fishes are monstrous because of their weird eyes, but it is their very eyes that helps them to survive in their environment.
Researchers solve mystery of deep-sea fish with tubular eyes and transparent head, by Bennett. K.M, Monterey bay aquarium research institute, 23 February 2009, http://www.mbari.org/news/news_releases/2009/barreleye/barreleye.html (assessed on 8 April 2010)
Weird Fish With Transparent Head, by Richard A. Lovett, National Geographic, 23 February 2009, http://news.nationalgeographic.com/news/2009/02/photogalleries/fish-transparent-head-barreleye-picture/ (assessed on 8 April 2010)
Deep water barreleye fish sports a clear canopy, by Edmund Jenks, 25 February 2009, http://oblate-spheroid.blogspot.com/2009/02/deepwater-barreleye-fish-sports-clear.html, (assessed on 8 April 2010)
Barreleye, Wikipedia, http://en.wikipedia.org/wiki/Barreleye, (assessed on 8 April 2010)
Crazy See-Through Fish Wows Scientists, by Caitlin Millat, Washington, 25 february 2009, http://www.nbcwashington.com/news/weird/Crazy-See-Through-Fish-Wows-Scientists.html, (assessed on 8 April 2010)