Monterey: Scientists from the Monterey Bay Aquarium Research Institute (MBARI) have recorded rare footage of a barreleye fish, a deep-sea creature famous for its transparent head and distinctive green eyes. The researchers spotted the unusual fish during an expedition in the Pacific Ocean, around 55 miles off Monterey Canyon, offering a rare opportunity to observe it in its natural underwater habitat.
The fish was found at a depth of approximately 1,970 feet, where the research team managed to observe and record it for around 20 minutes. The footage shows the creature floating underwater, with its green eyes clearly visible through the transparent covering of its head.
According to a report by the New York Post, the researchers were exploring the ocean aboard the vessel David Packard when they encountered the fish. The team used a remotely operated vehicle called Doc Ricketts to investigate and collect deep-sea creatures.
The sighting was particularly significant for the MBARI team because of how rarely the species is encountered. Despite spending four decades exploring the ocean depths, researchers at the institute had recorded only 10 previous encounters with the fish.
What makes the barreleye fish unusual?
Scientifically known as Macropinna microstoma, the barreleye fish is recognised for its unusual transparent head, through which its green eyes can be seen from outside.
The fish measures approximately six inches in length and inhabits the deep ocean, particularly the twilight and midnight zones. These regions receive little or no sunlight, making direct observation of marine life difficult.
Its transparent head is one of its most distinctive characteristics. Unlike many other deep-sea fish, whose external appearance can be difficult to study in their natural surroundings, the barreleye’s unusual anatomy makes it instantly recognisable when observed clearly.
The green eyes visible through its head give the creature an appearance unlike that of most familiar fish species. This distinctive feature has made it an object of interest for marine researchers.
The latest footage allowed scientists to observe the animal while it was alive and swimming in its natural environment, rather than relying only on specimens collected from the deep sea.
Researchers record rare 20-minute encounter
The MBARI team encountered the barreleye during an expedition in the Pacific Ocean. Researchers were aboard the institute’s vessel David Packard and operating the remotely operated vehicle Doc Ricketts to explore underwater environments.
The vehicle enabled the team to reach depths that are difficult for humans to access directly. During the exploration, researchers spotted the fish at approximately 1,970 feet below the surface.
They then recorded the creature for around 20 minutes. The resulting footage captured its appearance in considerable detail, including the transparent structure surrounding its eyes.
Deep-sea encounters of this kind are uncommon because many species inhabit areas far below the ocean surface. The limited availability of direct observations makes remotely operated vehicles important tools for documenting marine life.
For the researchers, the encounter provided an opportunity to study the barreleye without removing it from its natural environment. Observing the fish alive also helped preserve the appearance of its transparent head covering, an important feature that can be difficult to document through collected specimens.
Transparent head was missing from some historical drawings
Steven Haddock, the expedition’s senior scientist, described the barreleye as an extraordinary creature. He compared its appearance to something that might have been imagined by a child with a vivid imagination.
Haddock also highlighted an interesting problem associated with historical illustrations of the species.
According to him, earlier drawings based on specimens collected using fishing nets often showed the fish without its transparent head covering. As a result, the illustrations did not fully represent the animal’s distinctive appearance.
This made it difficult to understand that the drawings depicted the same species now recognised for its transparent head.
The latest observation was therefore particularly valuable because scientists could see the fish alive with its transparent covering intact.
Haddock described witnessing the creature in this condition as a real privilege. The encounter allowed the researchers to document a feature that was not always preserved or clearly represented in earlier observations.
Why deep-sea footage matters to marine research
The barreleye sighting highlights the challenges scientists face when studying animals that live in the deeper parts of the ocean.
The twilight and midnight zones are difficult environments to explore, and many of the creatures living there are rarely seen. Researchers often depend on specialised underwater equipment to observe these animals and record their behaviour.
The use of remotely operated vehicles allows research teams to investigate deep-sea habitats without requiring human divers to reach extreme depths. Such equipment can also provide visual records of animals in their natural surroundings.
For species such as the barreleye, these observations are especially useful because their physical characteristics can be difficult to understand from specimens alone.
The transparent head of Macropinna microstoma is a striking example. Historical illustrations that lacked this feature did not convey the animal’s full appearance, while the latest footage provided researchers with a clearer view of the living creature.
A rare glimpse into the ocean’s hidden world
The latest encounter adds to MBARI’s observations of a species that its researchers have seen only a limited number of times over four decades of deep-sea exploration.
Although the barreleye is known to science, sightings remain uncommon because of its deep-water habitat. The 20-minute recording off Monterey Canyon offered researchers a valuable opportunity to document its unusual appearance.
The footage also demonstrates how underwater technology is helping scientists observe marine species that would otherwise remain largely hidden from view.
With its transparent head and striking green eyes, the barreleye remains one of the more unusual creatures found in the deep ocean. The latest recording provides another rare look at this remarkable fish and the extraordinary diversity of life beneath the Pacific Ocean.