ROV film of a slow-moving barreleye fish deep beneath the surface of the Monterey Bay was acquired by researchers at the Monterey Bay Aquarium Research Institute.
I see a new Fresh from the Deep with my barreleye! During a dive with the Monterey Bay Aquarium, our education and outreach partner, the crew came across a rare treat: a barreleye fish (Macropinna microstoma).
When the ROV Doc Ricketts was released between 600 and 800 meters (2,000 and 2,600 ft) deep into the water, it discovered a dark-bodied fish with bright tubular eyes facing upwards within a transparent head. The researchers were compelled to inquire about the fish’s feeding habits because of the location of its eyes. They quickly discover that the peepers are moveable beneath their massive lids.
The barreleye can swivel its eyeballs behind that dome of translucent tissue, according to MBARI experts. They were able to get a live net-caught barreleye to the surface, where it was kept alive for many hours in a ship’s aquarium. The researchers were able to corroborate what they had seen in the ROV video: the fish rotated its tubular eyes as it twisted its body from a horizontal to a vertical position in this controlled setting.
They also learned how this strange-looking fish seeks for food.
The fish hangs still in the water most of the time, with its body horizontal and its eyes facing upward. The green pigments in its eyes may help the barreleye notice the bioluminescent glow of jellies or other creatures immediately overhead by filtering out sunlight coming directly from the sea surface. The fish shifts its eyes forward and swims upward in feeding mode when it sees prey (such as a floating jelly).