Black smoker chemistry and chemosynthetic ecosystems
Black smokers are hydrothermal vents where superheated water (up to 400°C, kept liquid by pressure) laden with dissolved metal sulfides erupts from the seafloor. Upon contact with cold seawater, metal sulfides precipitate to form the characteristic black "smoke." Chemolithoautotrophic bacteria use the reaction H₂S + ½O₂ → S⁰ + H₂O (and variations) as their energy source — supporting entire food webs without sunlight. First discovered in 1977 on the Galápagos Rift, these ecosystems challenged the assumption that all life ultimately depends on photosynthesis and transformed our understanding of life's potential on other worlds.