Extreme environments reveal much about the limits of life's adaptability, often highlighting the factors that are required to sustain life. A most unusual ecosystem is the global system of undersea volcanic ridges that define where the lithospheric plates are spreading apart. In the late 1970s scientists were amazed to discover ecosystems thriving thousands of meters beneath sea level in the absence of sunlight. These ecosystems occur around deep sea hydrothermal vents like those seen here. This beautiful active sulfide structure is located on the Juan de Fuca Ridge in the Northeast Pacific Ocean. Study of deep sea hydrothermal vent sites and the black smoker structures themselves will help scientists to understand how life originated on our planet and may originate on other planets.

Photo by Dr. Michael Perfit © University of Florida, and NOAA VENTS Program