Black smoker

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Black smokers are a type of hydrothermal vent found on the ocean floor. The vents are formed in fields hundreds of meters wide when superheated water from below the Earth's crust comes through the ocean floor. The superheated water is rich in dissolved minerals from the crust, most notably sulfides, which crystallize to create a chimney-like structure around each vent. When the superheated water in the vent comes in contact with the frigid ocean water, many minerals are precipitated, creating the distinctive black color. The metal sulfides that are deposited can become massive sulfide ore deposits in time.

Black smokers were first discovered in 1977 around the Galápagos 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 at the 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. 1.4 × 10¹⁴ kg of water is passed through black smokers each year.

Contents 1 Black smoker ecosystem 2 See also 3 External links 4 References

[edit] Black smoker ecosystem

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, methane, 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.

A species of phototrophic bacterium has been found living near a black smoker off the coast of Mexico at a depth of 2500 m. No sunlight penetrates that far into the waters. Instead, the bacteria, part of the Chlorobiaceae family, use the faint glow from the black smoker for photosynthesis. This is the first organism discovered in nature to use a light other than sunlight for the photosynthetic process (Beatty, et al., 2005).

New and unusual species are constantly being discovered in the neighborhood of black smokers: for instance, the Pompeii worm in the 1980s, and, in 2001, during an expedition to Indian Ocean's Kairei hydrothermal vent field, an armor-plated gastropod. The latter uses iron sulfides (pyrite and greigite) for the structure of its dermal sclerites (hardened body parts), instead of calcium carbonate. The extreme pressure of 2500 m of water (approximately 25 megapascals) is thought to play a role in stabilizing iron sulfide for biological purposes. This armor plating probably serves as a defense against the venomous radula (teeth) of predatory snails, co-existing in the same community. This snail, which is unique in its kind, has not yet been named to date.

[edit] See also

• Cold seep
• Hydrothermal vent
• Alvin submersible
• Lost City

[edit] External links

• Hydrothermal Vent Systems Information from the Deep Ocean Exploration Institute, Woods Hole Oceanographic Institution

[edit] References