Hadal zone
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| Aquatic layers | |
| Pelagic | |
| Photic | |
| Epipelagic | |
| Aphotic | |
| Mesopelagic | |
| Bathypelagic | |
| Abyssopelagic | |
| Hadopelagic | |
| Demersal | |
| Benthic | |
| Stratification | |
| Pycnocline | |
| Isopycnal | |
| Chemocline | |
| Halocline | |
| Thermocline | |
| Thermohaline | |
| Marine habitats | |
| Lake stratification | |
| Aquatic ecosystems | |
| Wild fisheries | |
The hadal zone (named after the realm of Hades, the underworld in Greek mythology), also known as the hadopelagic zone and trench zone, is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around 6,000 metres (20,000 ft) to the bottom of the ocean. The hadal zone has low population and low diversity of marine life.[citation needed]
Conditions
It is believed that most life at this depth is sustained by marine snow or the chemical reactions around thermal vents. The low nutrient level, extreme pressure and lack of sunlight create hostile living conditions in which few species are able to exist. As no sunlight reaches this layer of the ocean, deep sea creatures have reduced eyesight, with very large eyes for receiving only bioluminescent flashes. Most of the bottom-dwelling creatures lack pigmentation, because coloration is not useful in an environment with no light.
The most common organisms include jellyfish, viperfish, tube worms and sea cucumbers.[1] The hadal zone can reach far below 6,000 meters (20,000 feet) deep; the deepest known extends to 10,911 meters (35,814 ft).[2] At such depths (for example, at 36,000 feet below sea level) the pressure in the hadal zone exceeds 1,100 standard atmospheres (110 MPa; 16,000 psi).
Exploration
In 1960, Jacques Piccard and Don Walsh reached the bottom of the Mariana Trench, the deepest known trench on Earth, and observed life.[3] James Cameron also reached the bottom in 2012 using the Deepsea Challenger.[4]
See also
Notes and references
- ↑ Meeresboden - down under. February 1, 2007. (German)
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ ThinkQuest. February 1, 2007.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
External links
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