Hadal zone

From Wikipedia, the free encyclopedia

Hadal zone (or Hadopelagic zone) is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around 6000m (19,700 ft) to the bottom of the ocean. ‘Hadal’ is a French word meaning “house of the dead”, which is in turn from the Greek god Hades, the god of the dead, and his domain.

[edit] Conditions

In 1960, Jacques Piccard and Don Walsh reached the Marianas Trench, the deepest trench on Earth, and observed life.^[1] It is believed that most life at this depth is sustained by marine snow or the chemical reactions around thermal vents. The creatures that exist off of the thermal vents are called thermophiles and live at the base of submarine volcanoes. The lack of light and intense pressure create hostile living conditions, and few species have habituated to adapt to these conditions. As no sunlight reaches this layer of the ocean, deep sea creatures have adapted to with reduced eyesight, having very large eyes for receiving only bioluminescent flashes. Most of the bottom dwelling creatures lack any pigmentation and appear red due to blood showing through their skin, since coloration is not useful in an environment with no light.

The pressure here can reach over 1100 atmospheres (about 16,200 psi). Creatures removed from this zone will die in the lower-pressure areas above.^[2] The most common creatures include jellyfish, viperfish, tube worms also clams, and the deep sea angler fish.^[3]

[edit] Notes

1. ^ ThinkQuest. February 1, 2007.
2. ^ Death of a Hadal Deep-Sea Bacterium After Decompression. February 1, 2007.
3. ^ (German) Meeresboden - down under. February 1, 2007.