User:DiverDave/Deep sea communities
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The deep sea or aphotic zone is found at a depth of 1000 meters or more. The aphotic zone in turn consists of three subzones: the bathyal, abyssal, and hadal zones. The deepest place in the deep sea is the Challenger Deep, located at the bottom of the Mariana Trench near Guam. At a depth of 10,911 meters (35,798 feet or 6.77 miles), the barometric pressure is about 11,318 metric tons-force per square meter (110.99 MPa). If Mount Everest were submerged there, its peak would be more than a mile beneath the surface.
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Little or no sunlight penetrates to this depth, and most of the endemic organisms of the deep sea rely on falling organic matter produced in the photic zone above for subsistence. For this reason scientists assumed until recently that life would be sparse in the deep ocean. However, recent research has revealed that life is in fact abundant in the deep ocean.
The deep sea is an extremely hostile environment, characterized by barometric pressures between 20 - 1000 atmospheres, temperatures between -0.5°C - 4°C, and a relatively low oxygen concentration. Most fish that have evolved in this harsh environment are not capable of surviving under laboratory conditions, and attempts to study them alive in captivity have been unsuccessful thus far. For this reason little is known about them. As such, most species are known only to scientists and have therefore retained only their scientific names.
More is known about the moon than the deepest parts of the ocean.[1] Until the late 1970s little was known about the possibility of life on the deep ocean floor but the discovery of thriving colonies of shrimp and other organisms around hydrothermal vents changed that. Before the discovery of the undersea vents, all life was thought to be driven by the sun. But these organisms get their nutrients from the earth's mineral deposits directly. These organisms thrive in completely lightless and anaerobic environments, in highly saline water that may reach 300 °F (150 °C), drawing their sustainance from hydrogen sulfide, which is highly toxic to all terrestrial life. The revolutionary discovery that life can exist without oxygen or light significantly increases the chance of there being life elsewhere in the universe. Scientists now speculate that Europa, one of Jupiter's moons, may have conditions that could support life beneath its surface which is speculated to be a liquid ocean beneath the icy crust.