Twenty-five
years ago a group of geologists, geophysicists and geochemists ventured 330
kilometers (250 miles) northeast of the Galápagos Islands in search of
what at the time was only a theory: hydrothermal vents. Following the acceptance
of plate tectonics, scientists hypothesized that cold, dense oceanic water seeped
through cracks along underwater volcanic spreading ridges, where hot rocks heated
the water, allowing it to rise to the seafloor as underwater hot springs. Detailed
seafloor maps had given scientists an idea of where to search for evidence of
such springs, but none expected to find a unique community of animals calling
this underwater scene home. Tubeworms at the Galápagos Rift. Photo by John Edmond, MIT/WHOI.
No longer
were the abysmal depths remote places where animals were few and far between,
surviving primarily on what fell from the surface waters above. Here was a community
of animals surviving directly off of the chemicals and mineral-rich waters emerging
from Earth's oceanic crust. Finding a life cycle based on chemosynthesis and
not photsynthesis provided the impetus to examine the potential for such life
forms elsewhere on Earth and in our solar system. Bugs or bacteria living in
acidic environments, on ice or within the extreme temperatures of hydrothermal
vents are today known as extremophiles. 
