The Pacific barreleye fish, also known as Macropinna microstoma, is a fascinating creature that inhabits the deep, dark depths of the ocean. Its most distinctive feature is its transparent, fluid-filled shield on its head, which allows its eyes to be seen. This unusual adaptation has captured the attention of scientists and marine enthusiasts alike.
Initially, researchers believed that the barreleye fish's tubular eyes were fixed in place, limiting its vision to what was directly above its head. However, in 2008, scientists discovered that its eyes could rotate both up and forward within the transparent shield. This discovery was a significant breakthrough, revealing the fish's remarkable visual abilities and its unique hunting technique.
The barreleye fish is found at depths of around 600-800 meters (2,000-2,600 feet), where light is scarce. It spends most of its time hanging motionless in the water, using its large fins for stability and keeping its eyes directed upward. In this way, it can detect the silhouettes of potential prey that pass overhead.
When the barreleye fish spots prey, such as small fish or jellyfish, it rotates its eyes forward like binoculars and turns its body from a horizontal to a vertical position to feed. This behavior was observed by researchers Bruce Robison and Kim Reisenbichler from the Monterey Bay Aquarium Research Institute (MBARI), who speculate that the barreleye fish may steal food from siphonophores.
The barreleye fish's tiny mouth and large scales covering most of its body suggest that it is not an active predator. Instead, it relies on its visual acuity and slow movement to hunt for prey. Its transparent shield protects its sensitive eyes while allowing it to navigate through the murky depths.
The Pacific barreleye fish is a fascinating example of the incredible adaptations that marine life has evolved to survive in extreme environments. Its unique visual system has captured the imagination of scientists and nature enthusiasts, inspiring further research into the mysteries of the deep ocean.