Until 1977, scientists assumed almost all life on Earth depended on sunlight: plants photosynthesize, animals eat plants, predators eat animals, and the sun fuels the whole chain. Then a submersible exploring the deep Pacific stumbled onto something that broke the rule.
At cracks in the seafloor, geysers of superheated mineral-rich water - “black smokers” - were shooting up at temperatures over 400°C. And around them, thriving in pitch darkness, was an entire ecosystem: red-tipped tube worms two meters tall, giant clams, blind shrimp, ghost-white crabs.
These animals live entirely off chemicals. Bacteria at the base of the food chain don’t photosynthesize - they chemosynthesize, turning the hydrogen sulfide and other minerals in the vent water into energy. Many scientists now think life on Earth first started at vents like these, billions of years ago.
