Bizarre deep-sea fish with clear head only spotted nine times is caught on video

This is the astonishing moment a bizarre-looking fish that has only been seen nine times was caught on camera in the deep.

Scientists captured images of the unusual fish with a bulbous, translucent head and green eyes that peer through the forehead thousands of feet below the surface of Monterey Bay off California.

The odd-looking fish is known as a barreleye fish (Macropinna microstoma) and has only been spotted nine times by the researchers at the Monterey Bay Aquarium Research Institute (MBARI).

The team have used their remote operating vehicle on more than 5,600 dives to find the fish, they tweeted.

This odd-looking fish is known as a barreleye fish (Macropinna microstoma) has only been spotted nine times (MBARI (Monterey Bay Aquarium Research Institute))

Last week, the scientists caught the fish while cruising at a depth of 650 metres (2,132 feet) in the Monterey Submarine Canyon, which is one of the deepest submarine canyons on the Pacific Coast.

Thomas Knowles, a senior aquarist at the Monterey Bay Aquarium, told Live Science : "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."

He added: "We all knew that this was likely a once in a lifetime experience."

The barreleye's eyes are incredibly light-sensitive and are at the top of the fish's head (MBARI (Monterey Bay Aquarium Research Institute))

The creature's eyes are incredibly light-sensitive and are towards the top of the fish's head.

The two-dark coloured capsules in front of the fish's eyes are what helps to smell, the team said.

Barreleye fish can be found from the Bering Sea to Japan and Baja, California.

They live between 600 and 800 metres below the surface, or 2,000 to 2,600 feet, which is the depth near where the water goes into complete darkness.

This fish was captured beneath the surface of Monterey Bay off California (MBARI (Monterey Bay Aquarium Research Institute))

Scientists do not fully know how these gelatinous helmet-heads floats in the ocean.

Bruce Robison, an MBARI senior scientist, told Live Science: "We have no handle on population size, except in a relative sense."

Past observations have suggested the fish are mostly motionless and wait for prey, like zooplankton and jellyfish, to drift overhead.

Once it spots its prey it zooms upwards to snag it in its mouth.

Scientists speculate its head shield might protect it from the stinging tentacles of its prey.