Hydrothermal Vents
- erudite .
- Aug 15, 2022
- 2 min read
By Rita Dwivedi
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Hydrothermal vents are naturally-occurring structures found in the ocean. These vents form in volcanically-active areas, such as mid-ocean ridges and undersea mountain ranges, where the Earth’s tectonic plates are spreading apart and magma wells up to the surface or beneath the ocean floor. The ocean water that seeps into the crust is heated by the underlying magma. In the process, the water becomes hotter as well as more acidic, causing it to leach metals, such as iron, zinc, lead, cobalt, and copper from the surrounding rocks. The heated fluid reaches the surface through openings in the seafloor. As the fluid pours out of the vent, the fluids encounter cold, oxygenated sea water, causing another series of chemical reactions. Hydrothermal fluid can reach temperatures of 400°C (750°F) or more, making it difficult for life to survive. Sulfur and other materials come out of the solution to form metal-rich towers and deposits of minerals on the seafloor (1). Minerals coming out of a hydrothermal vent tend to include hydrogen sulfide or some other sulfur compound.
The environment in which these hydrothermal vents occur is so dark that photosynthesis cannot occur. In the deep sea, most of the food must sink from the sunlit surface of the ocean; however, as the food descends, it is eaten by a variety of organisms. As a result, there is very little food that actually makes it to the bottom of the deep seafloor. Regardless of this, there are still organisms, such as specialized bacteria, that can convert these sulfur compounds and heat into food and energy. As these bacteria multiply, they form thick mats on which other animals can graze. The bacteria and other animals can then form symbiotic relationships. For example, the bacteria may create energy for an animal like a giant tube worm or a yeti crab, while this animal gives the bacteria protection from predators (2).
Some scientists even hypothesize that the first life on Earth may have started in deep hydrothermal vents. Fossils of multicellular animals have been found dating back to over 500 million years ago, while the oldest animal fossils from hydrothermal vents are approximately 440 million years old. Some of the earliest evidence for microbial life on Earth comes from rocks found in Canada around four billion years (400 million years) ago. The hostile environment of the Earth’s surface at the time further suggests that life is more likely to have begun within the Earth’s crust or in the deep sea, making hydrothermal vents a likely candidate for the origin of life (3).
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