How Are Hydrothermal Vents Explored?

Hydrothermal Vents

Hydrothermal vents are geysers found in the deepest parts of the sea. They are home to unusual forms of life, including bacteria, giant tubeworms, eyeless shrimp and giant clams. More than 300 species have been discovered that can only be found at hydrothermal vents. The mineral-rich water that spews out can be as hot as 750 F and the organisms that live in the vents must also withstand the tremendous water pressure of the deep sea. Scientists believe that bacteria able to thrive in these extreme conditions could be the closest living relatives to the first life on earth, and the origin of life might have occurred in a similar environment.

No sunlight reaches these depths. Unlike all other life on earth, hydrothermal vent ecosystems are not based on energy from the sun. Instead of the familiar process of photosynthesis that supports us, vent organisms rely on chemosynthesis. Chemosynthetic bacteria break down sulfur from the vent water to release energy. Other vent organisms either eat these bacteria, eat other animals that eat the bacteria or have symbiotic relationships where bacteria live inside their bodies and provide nutrition directly to their tissues.

Hydrothermal vents are formed by the shifting of tectonic plates in the sea. When plates of the earth's crust move apart, seawater flows into the opening and is heated by the molten rock (magma) beneath the crust. As the water heats up, it rises and comes spurting back out through the hole. Vents called "black smokers" spew black water rich in iron and sulfide. There are also "white smokers" that emit white water full of calcium, barium and silicon. Some hydrothermal vents form rapidly growing chimneys when the minerals dissolved in the super-hot vent water suddenly solidify as they come into contact with the cooler sea water outside.

Hydrothermal vents were first discovered in 1977 using a small deep submergence vessel called Alvin. This sub can carry three people to depths up to 13,124 feet. Alvin features cameras, windows, searchlights, two maneuverable robotic arms that collect samples and place them into a basket attached to the outside of the sub, temperature probes, a magnetometer, sonar, a computer system, an apparatus called "the Sipper" for collecting water samples and other scientific instruments. The entire sub is about 23 feet long, and the titanium sphere where people can ride is six feet in diameter. Alvin was built in 1962 and cost $10 million. Alvin is still used to study hydrothermal vents and makes between 150 and 200 dives each year. It was also used to recover a lost 20-megaton H-bomb from the bottom of the Mediterranean Sea.