In the barely lit depths of the ocean, the four-eyed spook fish has caught scientists by surprise. This fish — wedged alive for the first time — is the only vertebrate recognized to use a mirror to focus an picture in its eye in its place of a lens.
Furthermore, the fish’s two eyes (not four, despite its name) are each split into two parts, one look up and one looking down, and each part is capable of focus an picture.
Only one other fish has been establish with such aptitude, but it uses two lenses, while the spook fish uses a lens on top and a mirror underneath.
The research side caught the four-inch fish while trawling for specimens between 2000 and 2,600 feet below the surface of the South Pacific, near the north island of New Zealand. The fish had been described as early as 1888, but none of the five researchers, with decades of deep sea diving knowledge among them, had ever seen one, and no live specimens had previously been record.
The team realizes they had amazing special when they photograph the fish from above and below and saw light reflected as of eyes in both directions. When they dissect the eye, they realized the lower part restricted a mirror, but no lens.