In 1977, scientists exploring a spreading ridge on the ocean floor near the Galapagos Islands found hot springs — and around them, to their amazement, crowds of organisms nobody had ever seen. Those springs were hydrothermal vents, and the life around them depends on the chemistry of seawater meeting molten rock.
A black smoker vents jets of fluid full of fine sulfide particles, formed as hot vent fluid mixes with near-freezing seawater. Credit: NOAA.
How a vent forms
Hydrothermal vents are hot springs produced by underwater volcanoes at spreading ridges and convergent plate boundaries — places where tectonic plates move apart or together. Cold seawater seeps down through cracks in the ocean crust, is heated by hot magma, and comes back up to form the vent. The water can reach more than 700 degrees Fahrenheit, yet it does not boil, because of the extreme pressure at the depths where vents form.
Smokers, black and white
When the hot fluid meets near-freezing seawater, minerals solidify as they cool and build chimney-like structures:
| Chimney | Built from | Color |
|---|---|---|
| Black smoker | iron sulfide | black |
| White smoker | barium, calcium and silicon | white |
Life fed by chemistry
The communities around vents depend on chemical processes that come from the interaction of seawater with the hot magma of underwater volcanoes.
Sources
Based on "What is a hydrothermal vent?" from NOAA's National Ocean Service, a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from oceanservice.noaa.gov
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