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Black smokers

A robot device samples the water blasted out from a black smoker. Snaking across the ocean floor is a vast undersea mountain chain known as the Mid-Oceanic Ridge. Here, the Earth’s crust is gradually spreading apart and magma, hot molten rock from beneath the crust, rises to the surface of the seabed. In some places along the Ridge, water seeping down into the rocks is heated by the magma. It shoots up through cracks in the ocean floor, known as hydrothermal vents. These jets of water are rich in minerals from the Earth’s crust, especially sulphur. As the minerals emerge, they are gradually deposited around the vents, creating tall chimneys. The sulphur turns the waters around the vents black, and gives these chimneys their name: “black smokers”. No one knew of their existence until 1977, when they were discovered by scientists near the Galapagos Islands in the Pacific Ocean.



Among the many species in the black smoker animal community are fish, crabs, lobsters, clams and giant tube worms.

Life without light

The temperature of the water shooting out of the black smokers can be around 300°C (570°F). In the warm, mineral-rich water close by, an amazing amount of life flourishes. Without sunlight to grow plants, life around the black smokers relies instead on bacteria, which convert the sulphur dissolved in the water into food. This process is known as chemosynthesis. The bacteria provide food for some animals, which are then prey for predators. Tube worms and giant clams actually have bacteria inside their bodies to make food for them, as they do not have mouthparts or guts to feed themselves. The existence of life around black smokers proves that life does not need to depend on sunlight to survive, as was previously thought.
 

Black smokers were first discovered in 1976 on the floor of the East Pacific Ocean at an average depth of 2100 m (6900 ft).

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