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Facts About Hydrothermal Vents

In 1977, the crew of the ALVIN, a research submersible, made a spectacular discovery. On the ocean floor near the Galapagos Islands was a hydrothermal vent, or underwater geyser. Over the past 33 years, more than 220 have been discovered in the Atlantic, Indian and Arctic Oceans.

Formation
- Hydrothermal vents form where there is volcanic activity. The tectonic plates that form Earth's crust shift, creating cracks in the ocean floor. Cold seawater seeps into these cracks and is heated by the magma beneath the crust. When this volcanically heated water rises and spews into the ocean, its temperature may be as high as 360°C.
Vent Fields
- Most hydrothermal vent fields have been discovered along the crest of the Mid-Oceanic Ridge, a 46,000-mile-long chain of underwater mountains. The largest field, called TAG, is the approximate size and shape of a football stadium.
Chimneys
- This super-heated water is a dark, chemical soup. Minerals precipitate out and harden on the rim of the vent, forming a tall, chimney-like structure, called a black smoker, over time. Chimneys can grow as much as 30 centimeters in a day. In 2000, scientists discovered a 55-meter-high chimney in the Lost City vent field in the Atlantic Ocean.
Organisms
- Hydrothermal vent fields teem with an array of diverse life forms. More than 300 new species have been identified. The most impressive creatures are giant tubeworms, which can grow up to 8 feet long. Other species include Alvinella worms, clams, crabs, limpets, mussels, octopus and shrimp.

Nature