A rare fish with a transparent forehead has been filmed by researchers at the Monterey Bay Aquarium Research Institute in California - and it is quite the sight.

The discovery was made by aquarist Tommy Knowles and his team while onboard the research vessel Rachel Carlson as they were collecting jellies and comb jellies for the upcoming “Into the Deep” exhibition.

In the midst of a dive, the barreleye fish (Macropinna microstoma) was spotted by the team for only the ninth time (which considering their remotely operated vehicles have logged more than 5,600 successful dives and recorded more than 27,600 hours of video, it’s not exactly a common occurrence).

Given the barreleye lives at depths of 600 to 800 metres (2,000 to 2,600 feet) in total darkness, this explains why sightings are few and far between.

Barreleye fish can grow to be up to 15 centimetres (6 inches) in size and live on a diet of zooplankton, including crustaceans and siphonophores and can be found in the Bering Sea, Japan and Baja California.

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“Two small indentations where eyes might normally appear on a fish are actually the barreleye’s olfactory organs, and its eyes are two glowing green orbs behind its face that gaze up towards the top of its head,” according to MBARI.

“Its eyes look upwards to spot its favourite prey—usually small crustaceans trapped in the tentacles of siphonophores—from the shadows they cast in the faint shimmer of sunlight from above.”

Perhaps, you’re wondering how the fish are able to eat their prey if their eyes look upwards...

While scientists previously thought the barreleye’s gaze was fixed looking straight up, MBARI researchers in 2009 were able to prove how the fish is able to rotate its eyes towards the front to see its food when eating.

For more information about the bizarre fish, visit the MBARI website.

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