Black smoker
From Wikinfo
Black smokers are a type of hydrothermal vents found on the ocean floor. Generally hundreds of meters wide, black smokers are formed when superheated water from below the Earth's crust comes through the ocean floor. They are rich in dissolved minerals from the crust, most notably sulfides, which crystalize to create a chimney-like structure around the vent. When the superheated water in the vent comes in contact with the frigid ocean water, many minerals are precipitated from the vent, creating the distinctive black color.
Black smokers were first discovered in 1977 around the Galapagos Islands by the National Oceanic and Atmospheric Administration. They were observed using a small submersible vehicle called ALVIN. Today, black smokers are known to exist in the Atlantic and Pacific Oceans, at an average depth of 2100 meters. The temperature of the water they vent can reach 400�C, but does not boil due to the high pressure it is under at that depth. The water is also extremely acidic, often having a pH value as low as 2.8 -- approximately that of vinegar.
Although life is very sparse at these depths, black smokers are the center of entire ecosystems. Sunlight is nonexistent, so many organisms -- such as archaea and extremophiles -- must convert the heat and sulfur compounds provided by black smokers into energy through a process called chemosynthesis. In turn, more complex life forms like clams and tubeworms feed on these organisms. The organisms at the base of the food chain also deposit minerals into the base of the black smoker, thus completing the life cycle.
See Also
References
- Adapted from the Wikipedia article, "Black_smoker" http://en.wikipedia.org/wiki/Black_smoker, used under the GNU Free Documentation License
