Living Without Sunlight

For centuries, scientists assumed nothing could survive in the deep ocean. No sunlight means no photosynthesis, and no photosynthesis means no food. That assumption collapsed in 1977 when researchers aboard the submersible Alvin found thriving ecosystems around hydrothermal vents on the Galapagos Rift.

These communities are powered by chemosynthesis — bacteria that extract energy from chemical reactions involving hydrogen sulfide, methane, and other compounds. These microbes form the base of an entire food web that exists without a single photon of sunlight.