Researchers aboard the deep-sea submersible Alvin are best known for discovering thriving ecosystems around deep-ocean hydrothermal vents, including giant tube worms and other life that survive without sunlight by using chemosynthesis instead of photosynthesis.

What Alvin’s Researchers Discovered

In 1977, scientists using Alvin explored the Galápagos Rift and found hydrothermal vents on the seafloor that were ejecting superheated, mineral- rich fluids, like underwater geysers. Around these vents they observed dense communities of organisms—such as giant tube worms, clams, and crabs—living in total darkness at great depth.

Why This Discovery Matters

The most important part of this discovery was that these organisms did not rely on sunlight; instead, bacteria used chemicals from vent fluids to produce energy in a process called chemosynthesis. This overturned the long-held idea that all complex ecosystems on Earth ultimately depend on sunlight and expanded scientific ideas about where life can exist, including in extreme environments on other worlds.