These ideas changed dramatically in the 1970's. There they discovered scalding water billowing up from hydrothermal vents on the seafloor. Surrounding these underwater geysers were clusters of bizarre animals that were completely new to science, including tubeworms, giant clams, and ghostly white crabs. Hydrothermal vents Hydrothermal vents form in places where there is volcanic activity. They are most often found along the global mid-ocean ridge system where tectonic plates are spreading apart and new oceanic crust is being created.
Seawater seeps down through cracks in the ocean floor and circulates deep into the ocean crust.
The scalding water reacts with rocks in the ocean crust, picking up sulfides and dissolved metals, such as copper, zinc, and iron. Photo by Dan Fornari Because hot water is more buoyant than cold water, it rises up through the ocean crust and jets out the vent openings. When this hot hydrothermal fluid mixes with the cold oxygenated seawater, the metals carried up by the fluid react with sulfides to form black minerals. The question of how organisms on the seafloor get enough energy puzzled scientists for a long time. Sunlight does not reach the hydrothermal vents, so organisms cannot manufacture sugars through photosynthesis.