The Pacific barreleye fish, scientifically known as Macropinna microstoma, is a fascinating creature that dwells in the depths of the ocean, between 600 to 800 meters below the surface. Unlike most animals with eyes positioned on the surface of their faces, the barreleye fish has unique tubular eyes that are situated within its face. These eyes are topped with incredibly light-sensitive domes, pointing upwards and enclosed in a transparent cockpit on its forehead.
Despite their mysterious nature, there is still much to learn about these enigmatic fish. One interesting fact is that for many years, scientists believed that the fish’s eyes were fixed in position, similar to the tubular eyes of owls. However, in 2009, it was discovered that the barreleye fish can actually move its eyes forwards. This ability allows them to effectively navigate their dark environment and spot potential predators and prey.
The eyes of the barreleye fish are a powerful tool that aids in their survival. With large lenses and a high number of rod cells (and no cones), these eyes are well-equipped to collect as much light as possible in the dimly lit depths where they reside. The transparent domes that encase their eyes likely serve to protect them from the stinging cells of their prey and enhance light collection, functioning akin to a magnifying glass.
In addition to the Pacific barreleye fish, two other species of barreleye, Rhynchohyalus natalensis and Dolichopteryx longipes, are the only known vertebrates that utilize mirrors to focus their eyes. This unique adaptation showcases the incredible diversity and ingenuity of these deep-sea creatures.
Despite the limited amount of light that reaches the depths where they live, barreleye fish have adapted to make the most of their environment. Their flat fins allow for precise maneuvering, enabling them to hover motionless in the water as they search for prey. With tiny mouths for precision feeding and a large digestive system capable of handling a wide variety of drifting prey, including plankton, jellies, and crustaceans, these fish are well-equipped to thrive in their dark and mysterious habitat.
Encounters with barreleye fish are rare during ocean expeditions, but each sighting offers new insights into their unique adaptation and survival strategies. These tenacious little survivors have found a way to thrive in the eerie darkness of the deep ocean, showcasing the remarkable diversity of life on our planet.
