Bizarre and Rarely Seen Fish with Translucent Head and Glowing Eyes Filmed off California

A rarely seen and bizarre deep sea fish with a see-through head and big glowing green eyes has been filmed off the coast of California.

The barreleye fish was spotted during a dive organized by the Monterey Bay Aquarium Research Institute (MBARI) and the Monterey Bay Aquarium.

The MBARI said it was only the ninth time this species had been observed during its 5,600 dives and 27,600 hours of footage from the region.

The barreleye fish, Macropinna microstoma, was filmed in the twilight zone, between 2,000 and 2,600 feet beneath the ocean surface.

The 54-second video shows the unusual fish, with a translucent head and tail, and brown-colored body, swimming around. Close-ups show two large glowing spheres inside its head. These, the MBARI said, are the creature's eyes.

The two small indentations where you might expect the eyes to be are actually its olfactory organs.

"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," a statement from the MBARI said

"But how does this fish eat when its eyes point upward and its mouth points forward? MBARI researchers learned the barreleye can rotate its eyes beneath that dome of transparent tissue."

Barreleye fish were first described in 1939. The species grows up to around six inches in length. They are found in oceans across the world, from the waters of Japan to Baja California.

It is thought barreleye fish hover below siphonophores so they can steal their food. Siphonophores are unusual marine organisms that can grow up to 33 feet in length and drift around the ocean with thousands of stinging tentacles that are used to capture small animals.

Barreleye fish are mostly motionless in the water, with its body horizontal and its eyes looking upwards. When it sees prey caught in the siphonophore tentacles, it rotates its eyes forward and swims up to get it.

The fish does not produce light like some other deep sea creatures. The glowing seen in the video is from the remote operated vehicle used in the dive shining on light colored tissue underneath a transparent dome, the Monterey Bay Aquarium said.

"Picture the blue-green body parts as upward facing eyes underneath a clear dome like an astronaut helmet," it said in a Facebook post. "The blue-green color to the eyes are pigments to help them find their bioluminescent prey."

barreleye fish
Stock image of a barreleye fish. Researchers filmed a barreleye off the coast of California during a recent expedition. Getty Images