Since my childhood I love to read about nature and animals, I turn on the TV only to watch scientific programs about them. So sometimes I think that I am hard to surprise with something or someone extraordinary, and of course I understand that I'm wrong.
The scientists almost every day discover new species of living organisms, and if remember that the World Ocean studied by only 3-4%, and not difficult to understand that there will be many more unusual and surprising discoveries ahead. And here is one of them:
Marcopinna Microstoma (Barreleye)
This species was discovered in 1939, but scientists were able to take pictures of live fish only 11 years ago. She lives in the Northern Pacific ocean at depths of 500-800 meters, reaches only 15 inches in length, her body is covered in dark scales.
The most interesting: Marcopinna Microstoma has a transparent skull, through which you can see her brains, literally.
Actually, it's not even a skull, and a transparent dome-shaped shell, which is attached to her back, sides and fins. This dome protects the internal organs from the pressure at great depths. Because of it, scientists couldn't study this species in detail: during ascent to the surface, the protective sheath is destroyed due to the pressure drop, and the fish immediately dies.
The pressure at the depth of her habitat in 81 times more than on earth.
At first glance, it may seem that she has a rather sad look, but the eyes are two green ball inside the head, and the holes in front of the muzzle are the olfactory receptors.
The green color is due by a special yellow pigment, which provides a filtering of light, coming from above, and lowers its brightness.
The structure of the eyes allows to change its direction from vertical to horizontal position, thus Marcopinna Microstoma has a very broad overview, and can see prey that is above and ahead.
A-vertically, B-horizontally
Today the basic version of such an unusual head structure is the protection from Siphonophorae's poison, on which Marcopinna microstoma preys. Evolution has ensured that her sensitive body parts are safe from the poisonous tentacles. Another interesting fact: the greater the depth of habitat of this fish, the large size she can reach.
sources: Macropinna Microstoma WiKi, Macropinna Microstoma transparent head, Fish with transparent head, imgaes from Google search