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| Photo cred: Flickr account GreenAnswers.com |
So much effort and time has gone into space exploration and the search for extraterrestrial life. However, there is still so much left to be explored on our earth alone. One extraordinary organism found in the tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans is the barreleye or "spook" fish.
With their clear heads exposing their bright green lenses and their black olfactory organs (nostrils), these fish do appear quite spooky! Barrelfish inhabit the ocean at moderate depths from 400 to 2,500 meters deep, just below the limit of light penetration. As an adaptation to the limited light source, barreleyes have distinct transparent heads. Their clear domes allow more light to reach their telescoping eyes, which protrude from their skulls. Their eyes are thought to mostly point upwards to allow them to detect any prey in the water above. However when they do spot food, they can rotate their eyes forward so they can coordinate their attack with their toothless mouths. Although barreleye fish have a rather large field of vision, they can really only detect the silhouettes of their prey because the retinas in their eyes consist of only rod cells and not cone cells. This is because rods are responsible for detecting images in low lighting and cones operated under high lighting and detect color.
Not only is this creature's transparent dome useful for viewing objects above it, but it also most likely protects it from the stinging cells of siphonophores, the organism it scavenges food from. Colonies of siphonophores look similar to jellyfish, and their tentacles house food that the barrelfish can easily steal.
Their unique eyes and transparent dome are obviously a clever product of evolution. Even though these creatures were first identified in 1939, their mysterious clear heads were not noted until much later because when brought to the surface, their fragile domes collapsed. If new information is being discovered on identified and new organisms frequently, then one can only imagine what else our Earth holds to uncover!
Watch the video of a live barrelfish below!
Their unique eyes and transparent dome are obviously a clever product of evolution. Even though these creatures were first identified in 1939, their mysterious clear heads were not noted until much later because when brought to the surface, their fragile domes collapsed. If new information is being discovered on identified and new organisms frequently, then one can only imagine what else our Earth holds to uncover!
Watch the video of a live barrelfish below!
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