Scientists have obtained film of a fish with a bulbous, translucent head and green orb-like eyes peering out through its forehead thousands of feet beneath the surface of Monterey Bay off the coast of California.
A barreleye fish (Macropinna microstoma) is a rarely seen and strange organism.
Researchers at the Monterey Bay Aquarium Research Institute (MBARI) have only sighted the species nine times despite sending their remotely operated vehicles (ROV) on over 5,600 dives into the fish’s habitat.
Last week, a team of scientists used MBARI’s ROV Ventana to spot a barreleye fish suspended in the ocean.
According to Thomas Knowles, a senior aquarist at the Monterey Bay Aquarium, the ROV was cruising at a depth of roughly 2,132 feet in the Monterey Submerged Canyon, one of the deepest submarine canyons on the Pacific coast, at the time.
He said, “The barreleye first appeared very small out in the blue distance, but I immediately knew what I was looking at. It couldn’t be mistaken for anything else.”
As the control room buzzed with anticipation, Knowles kept the ROV camera focused while ROV pilot Knute Brekke kept the underwater robot pointed at the barreleye.
The barreleye’s eyes flashed bright green in the light of the ROV and could be seen clearly through the translucent, fluid-filled shield that covered the fish’s head.
According to MBARI, these eyeballs are highly light-sensitive and can be positioned straight up, towards the top of the fish’s head, or straight forward. In addition, two dark-colored capsules sit in front of the fish’s eyes and contain the organs the animal uses to smell.
The Bering Sea to Japan and Baja California are all home to the barreleye fish.
According to MBARI, barreleyes live in the ocean twilight zone, about 650 to 3,300 feet beneath the ocean surface; specifically, barreleyes live about 2,000 to 2,600 feet beneath the ocean surface, near the depth where the water plunges into complete darkness.
According to previous studies by MBARI researchers, published in the journal Copeia in 2008, barreleye fish are mainly stationary as they wait for unwary prey such as zooplankton and jellyfish to drift above. A set of broad, flat fins that protrude out from the fish’s body allow it to hover in this manner.
Barreleyes can identify the silhouettes of their victims from above by directing their verdant eyes straight upward, and the green color in their eyes likely helps filter out sunlight from the ocean surface, Live Science reported.
When a barreleye fish sees a bioluminescent jelly or a small crustacean float by, it zooms upward to catch it in its mouth while moving its eyes forward to observe where it’s going.