The ocean is one of the mysteries that humans have not been able to fully explore.
Deep beneath the ocean, countless rare creatures exist and have strange appearances due to evolution to adapt to living environments where light does not reach.
Barreleye fish is one of the rare species found in the deep sea with its surprising appearance: A transparent head.
Rare barreleye fish was filmed by researchers at the Monterey Bay Aquarium Research Institute in California during a dive.
Aquarist Tommy Knowles was the first person in this group to see the rare barreleye fish while they were collecting jellies and comb jellies for the upcoming “Into the Deep” exhibition.
According to the experts, the barreleye fish was just spotted for only the ninth time out of 5,600 successful dives and recorded more than 27,600 hours of video.
This report also proves that seeing the rare barreleye fish is not easy.
The weird appearance of the rare barreleye fish
Barreleye fish have a transparent head with eyes like mesmerizing emerald balls.
This dome-like forehead has a shape like giant spherical lenses resting on a pair of long silver eye tubes. Therefore, it has the common name barrel-eye fish (Macropinna microstoma).
The green color inside the head acts as a kind of sunglasses, helping them find prey.
The tubular eyes are super sensitive allowing them to capture as much light as possible, facilitating to adapt with the darkness of the twilight zone.
According to previous studies, the eyes of barreleye fish are fixed above the head with their side facing up.
The strange thing is how they can still swallow prey right in front of them even when their eyes are facing upward.
Finally, scientists were able to explain this strange phenomenon
Barreleye fish can roll their eyes forward to see food when eating. This was amazing!
It always puzzled me that their eyes aimed upward, but the field of view did not include their mouths, Robison stated.
Two small indentations where eyes might normally appear on a fish are 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 favorite prey—usually, small crustaceans trapped in the tentacles of siphonophores—from the shadows they cast in the faint shimmer of sunlight from above, the group of scientists added.
Where does the rare barreleye fish live?
This rare creature lives in depths up to 600 to 800 meters (2,000 to 2,600 feet) in complete darkness.
The rare barreleye fish is not the biggest fish that lives in this depth of the sea.
In reality, they can grow up to 15 cm (6 inches) and often eat zooplankton, including crustaceans and siphonophores, to survive.
Although they can be found in the Bering Sea, Japan, and Baja California, it is really hard to see them even once.
