top of page

Bizarre Transparent Fish That Sees Through Its Own Head Captured in Rare Footage

By: April Carson

Scientists recently captured video of a fish with a bulbous, translucent head and green orb-like eyes that peek out through its forehead while diving millions of feet beneath the surface of Monterey Bay off California.

A barreleye fish (Macropinna microstoma) is an extremely uncommon sight. Despite having sent their remotely operated vehicles (ROVs) on more than 5,600 dives in the fish's habitat, the species has been observed just nine times by researchers with the Monterey Bay Aquarium Research Institute (MBARI), according to MBARI.

Last week, a group of scientists deployed MBARI's ROV Ventana and observed a barreleye fish suspended in the ocean.

The ROV was operating at a depth of roughly 2,132 feet (650 meters) in the Monterey Submarine Canyon, one of the Pacific coast's deepest submarine canyons, according to Thomas Knowles, a senior aquarist at the Monterey Bay Aquarium.

"The barreleye unexpectedly appeared tiny in the blue distance, but I recognized it immediately. It could not be confused for anything else," he added.

As the control room erupted in cheers, Knowles kept the ROV camera focused while Knute Brekke piloted the underwater robot toward the barreleye. "We all recognized that this was most likely a once-in-a-lifetime opportunity," Knowles added, because the elusive creature is so unusual.

In the ROV's light, the barreleye's eyes were a brilliant green and could be readily seen through the transparent, fluid-filled helmet that covers the fish's head.

According to MBARI, these eyes are extremely light sensitive and can be positioned straight up or straight ahead depending on the viewing angle. In either case, two dark-colored capsules are visible in front of the fish's eyes and contain the organs it uses to smell.

The barreleye fish's range extends from the Bering Sea to Japan and Baja California. Barreleyes dwell in the ocean twilight zone, which is located roughly 650 to 3,300 feet (200 to 1,000 m) beneath the surface of the sea; barreleyes are most often found between 2,000 and 2,600 feet (600 and 800 m) below the surface of the water.

The exact number of these gelatinous helmet-heads that float unseen in the sea's depths is unknown.

"We don't have a handle on population size, only in a relative sense," Bruce Robison, an MBARI senior scientist, noted to Live Science in an email.

Barreleyes are uncommon compared to other well-known twilight zone fish like lanternfish and bristlemouths, with the MBARI team finding barreleye fish about as frequently as they do anglerfish, whalefish, and gulpers.

According to MBARI research published in 2008 in the journal Copeia, barreleye fish are believed to mostly remain motionless while waiting for unsuspecting prey like zooplankton and jellyfish to drift overhead, based on previous observations. Its body is partially covered in tiny bumps, which help it stay aloft. Its broad, flat fins extend out from its body and allow it to hover in this manner.

Barreleyes can spot their prey from above by pointing their green-eyed gaze straight up, and the green pigment in their eyes may assist them see the dark ocean surface.

A barreleye fish will immediately grab a bioluminescent jelly or tiny crustacean with its mouth as it rises to capture the creature in its jaws and turn its eyes forward, so that it may see where it's going.

According to a 2009 MBARI video, scientists believe that M. microstoma may occasionally snatch food from siphonophores - jellyfish-like creatures that cling together in long lines and capture prey in their tentacles.

The barreleye fish's transparent head shield might protect it from the stinging cells in the siphonophores' tentacles, but this is pure supposition.

"Most aspects of their natural history are yet unknown, and much of what we believe we know about them is based on speculation," added Robison.

Fishers have been catching these translucent-headed fish in nets since the late 1930s, resulting in the destruction of their head shields. Prior to the 2000s, scientists were unaware of the shields because they had never previously encountered them in a barreleye fish's natural habitat. There is still much to learn about the unusual animal.

The team eagerly stared at the M. microstoma sample until it swam away and resumed their search for jellies and comb jellies in the deep sea on their most recent dive.

"We had no desire to capture the animal," Knowles added, as the aquarium is not yet well set up to care for the misunderstood fish.

However, many other strange and amazing creatures from the deep sea will be on display at the aquarium in the near future.

In 2022, the Monterey Bay Aquarium will debut a new exhibit called "Into the Deep: Exploring Our Undiscovered Ocean," which will feature creatures from all across the deep sea, including gigantic isopods, sea spiders, and blood-belly comb jellies.

Some of them resemble something plucked straight out of a science fiction novel, much like the barreleye fish.

Trauma and why it’s important to address it so you can manifest your best life


About the Blogger:

April Carson is the daughter of Billy Carson. She received her bachelor's degree in Social Sciences from Jacksonville University, where she was also on the Women's Basketball team. She now has a successful clothing company that specializes in organic baby clothes and other items. Take a look at their most popular fall fashions on

To read more of April's blogs, check out her website! She publishes new blogs on a daily basis, including the most helpful mommy advice and baby care tips! Follow on IG @bossbabymav





bottom of page