Evolution

The deep water barrel-fish, Macropinna microstoma, is one of those amazing examples of evolution taking a very peculiar path to adapt to a challenging environment.

You might think that the eyes of this fish are the two dark objects just above the mouth, but you'd be wrong.  Those are nostrils.  The lenses of the eyes are the two green globes inside the transparent head.

This fish lives in water almost completely black.  The eyes are extremely sensitive and are used, it is believed, to see the dim silhouette of prey above the head.  Originally it was thought that these fish could only see directly upward.

Robinson and Reisenbichler at the  Monterey Bay Aquarium Research Institute have just published a paper in which they have established that, in fact, the eyes can rotate forward when needed so the the fish can see what it is eating.

Amazing, perhaps, but not so amazing that this fish exists at all.  To see a short video of this fish, click here (see Feb 23, 2009 New Release if not available immediately on the home page).

Photo credit: Monteray Bay Aquarium.