Black smokers are some types of hydrothermal vents found at the bottom of the ocean. They usually form at about 3 km (2 miles) below sea level. Black smokers develop near volcanically active regions, such as in the mid-ocean ridges and emit high levels of sulfides, which precipitate when in contact with cold ocean water, forming chimney-like structures around a vent. The dissolved chemicals support bacteria, which forms the base of a food chain for larger marine animals. Black smokers were discovered for the first time in the ocean ridge near the Galapagos Island in the Pacific. Many have been discovered afterwards in the Pacific, as well as in other oceans of the world.
Formation of black smokers
Black smokers are formed when water seeps into fractures in the ocean’s crust near an active spreading ridge, where water may reach temperatures of over 450 °C and the water pressure may be of over 200 atmospheres. The high pressured water comes out at a hydrothermal vent, carrying minerals from the oceanic crust. Upon escaping at vents on the sea floor, the heated water comes in contact with the cold ocean water, depositing the sulfide minerals in stacks, and forming black chimney-like structures, which can grow as high as 60 meters (17 ft.) in height.
Life on the ocean floor
The energy from the Sun cannot penetrate at depths at which black smokers are found, therefore, another source of energy should exist for life to thrive at such depth and pressures. Black smokers support an abundance of biological life by providing the sulfur and methane compounds that small organisms, such as archae and extremophiles, convert into energy in a process known as chemosynthesis. These organisms form the base of the food chain for larger organisms, including tube worms, clams, crabs and fish. It is believed that early life could have resembled the microorganisms thriving around black smokers.
When the heated minerals and water come on contact with cold ocean water, they produce a cloud of dissolved manganese, iron, lead, zinc, copper, cadmium and cobalt, which can be as high as 1 km (0.6 miles) and 40 km (25 miles) across. Hydrothermal vents usually form small mounds of about 100-200 meters (328-656 ft.) across and approximately 20 meters (66 ft.) high, with clusters of black smokers occupying the central area of this dunes. Another type of hydrothermal vent known as a white smoker usually forms in the central area of the mound, depositing iron oxides and iron-zinc sulfides. These type of vents tend to produce lower temperature plumes.
New species discovered
New and unusual species of organisms are being discovered close to black smokers, such as one found at a depth of over 2,500 meters (8,200 ft.). Even though, no sunlight can penetrate to this depth, the bacteria were found to use the glow from a black smoker as a source for photosynthesis. Some of the bacteria thriving in black smokers resemble those primitive organisms known to have developed in the early Earth. This suggests that early life may have been similar to life thriving around black smokers. Scientists believe that studying black smokers may give them a clue to the origin of life on Earth.
Organisms in hydrothermal vents depend on chemosynthetic bacteria to survive. The water coming out from hydrothermal vents is highly rich in dissolved minerals, sustaining large populations of chemosynthetic bacteria. These bacteria form the base of a food web, attracting other organisms, including copepods and amphipods, which feed on these bacteria. Other organisms, including shrimps, snails, octopuses, crabs and tube worms, form part of the food chain in the black smoker habitat. Tube worms live in a mutualistic relationship with chemosynthetic bacteria. According to ceoe.udel.edu, the organisms living around black smokers may contribute to the development of new drugs and other products useful to man.
