The researchers risked descending to such great depths to study hydrothermal vents at the edges of continental plates. Hydrothermal vents are holes in the sea floor that allow superheated water from within the crust of the earth to escape into the ocean, much like hot springs on land. The water issuing from these vents can be as hot as 350 degrees Celcius. Water normally boils at 100 degrees Celcius, but the pressure is so great 2,500 meters below the surface that gas bubbles cannot form, and the water does not boil. The water is heated by the molten rock that makes up the mantle of our planet.
Water is forced through minute cracks in the earth s crust where it dissolves out many minerals.
The minerals are then carried with the water to the surface of the sea floor where they are spewed from cracks in black plumes. The bacteria that perform this feat are termed chemoautotrophic because they are able to produce useful energy from inorganic chemicals. Other organisms have evolved to make use of the bacteria by consuming them, starting a food web at the bottom of the ocean that appears to be totally independent of the sunlight-powered food webs at the surface. Researchers studying vent communities report meter-long tube worms and clams the size of footballs that feed off the bacteria. Recent trips have generated some very exciting news about hydrothermal vents .