see through fish

This fish is bananas!

The "barreleye" fish gives a new meaning to "clear-headed" -- members of the central California species Macropinna microstoma have fully transparent skulls filled with a jelly-like fluid that scientists discovered this week allows the fish 360-degree vision.

The barreleye (Macropinna microstoma for you ichthyologists) is a deepwater fish that has a see-through, fluid filled head in which it moves its eyeballs. And that, dear reader, is freaking awesome.

The common name for the fish is "barreleyes." Monterey Bay Aquarium Research Institute investigators recently figured out why this species has such an unusual head. Its eyes can actually rotate within its "skull," so the transparency allows the wary swimmer to keep a literal eye on happenings above it, as well as to the sides and directly in front.

You read that right, transparent skulls.

Scientists had announced Monday that they had solved a nearly 50-year mystery behind the fish, explaining that the neon green, bulbous eyes inside their see-through heads can fully rotate - dispelling previous claims that their eyes were stuck in "tunnel vision."

Using video cameras, MBARI researchers Bruce Robison and Kim Reisenbichler revealed the fish's eye movements. When remotely operated vehicles approached the fish, its eyes glowed a vivid green shade in the bright lights of the ROVs. Usually the fish were just hanging out motionless under the deep waters offshore California's central coast.

The eyes of the barreleye fish are extremely light-sensitive, so the fish tend to swim close to the depths of the ocean - making it hard to study the species, researchers said.

Newly developed vehicles designed for deep-sea research allowed the scientists access to the bottom-dwellers. They carefully brought one fish ashore and determined they had been wrong for nearly half a century about the fish's sight capabilities.

The barreleyes also have flat fins that let them remain motionless in the water - any sudden or intense movement can upset their fragile "headgear."