In the Monterey Bay off the coast of California, scientists recently saw a fish with a bulbous head and eyes that looked out through its forehead. The fish was filmed a few thousand feet below the surface.

This weird fish, called a barreleye fish, is only seen very rarely. Despite sending its remotely operated vehicles (ROVs) on more than 5,600 dives in their fish’s habitat, the Monterey Bay Aquarium Research Institute (MBARI) claims to have only spotted the species nine times.

However, there was some positive news last week. MBARI scientists used their ROV Ventana to spot a barreleye fish sticking out of the sea.


As Live Science puts it, at the time, the ROV was cruising about 2,132 feet (650 meters) down in one of the Pacific Coast’s deepest submarine canyons. The ROV was in the Monterey Submarine Canyon when it happened, which is one of the deepest submarine canyons on the Pacific Coast.

“The barreleye looked very small at first, but I knew what I was looking at right away. Many people didn’t know what it was. “He said that.

Knute Brekke, the ROV pilot, kept the underwater robot directed towards the barreleye while Knowles kept the ROV camera in focus. “We all realized this was possibly the only time we’d ever see this animal,” Knowles says.

Bright green eyes could be seen through the clear, fluid-filled shield covering the barreleye’s head. The ROV’s lights made the eyes glow bright green.

MBARI says these eyes are very light-sensitive. They can be positioned straight up, toward the top of a fish’s head, or straight ahead, the group says. The fish has two dark-colored capsules in front of its eyes that hold the parts of its body that smell.

The barreleye fish can be found from the Bering Sea to Japan, and from Baja California to Japan. The barreleye fish, according to MBARI, lives roughly 2,000 to 2,600 feet (600 to 800 meters) below the ocean’s surface. This is the point at which the water disappears completely.

These helmet-headed gelatinous things are hard to figure out how many there are in the ocean.

It’s hard to get a handle on population size “except in a relative sense,” Bruce Robison of the MBARI told Live Science in an email.

He said the MBARI team runs into barreleye fish about as often as they run into anglerfish, whalefish, and gulpers, “which is very rare.”

Scientists think barreleye fish stay still most of the time as they wait for prey, like jellyfish and zooplankton, to pass by. This is based on observations made by MBARI researchers in 2008 in the journal Copeia. The fish can float this way with broad, flat fins that spread out from its body.

Barreleyes can see the silhouettes of their prey from above because they point their green eyes straight up. The green pigment in their eyes may help block out sunlight from the ocean surface.

To get a bioluminescent jelly or tiny crustacean in its mouth, the barreleye fish flies up and moves its eyes forward. This way, the fish can see where it’s going.

Scientists believe M. microstoma steals food from siphonophores, which are jellyfish-like organisms that cling together in long lines and seize prey with their tentacles. This is based on an MBARI video from 2009.

The barreleye fish’s transparent head shield may protect it from the stinging cells in the siphonophores’ tentacles, but this is just a suggestion, not a fact.

“We don’t know very much about them, and much of what we think we know about them is based on educated guesswork.”

The first specimens of M. microstoma were discovered in 1939. Fishermen snagged these early fish in nets, destroying their clear head shields. Scientists didn’t know about the guardians until the 2000s. MBARI scientists learned about barreleye fish after seeing one in its natural habitat, he said. Right now, the strange fish have a lot more to learn.

The team was particularly fascinated by the M. microstoma specimen until it swam away on their last dive, after which they continued exploring for jellyfish and comb jellyfish in the deep water.

“We didn’t want to get this fish,” Knowles said because the aquarium isn’t set up to care for the fish that aren’t very well known.

That said, the aquarium will soon have a lot of other weird and wonderful creatures from the deep sea on show.

New exhibit “Into the Deep: Exploring Our Undiscovered Ocean” will be unveiled at the Monterey Bay Aquarium in the spring of 2022. According to the aquarium’s website, it will house a wide range of deep-sea species, including enormous isopods, sea spiders, and blood-bellied comb jellyfish.

It also looks like something from a sci-fi book.


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