A microbial garden beneath the seafloor

Recent discoveries have raised the possibility of a huge and diverse subsurface biosphere of microbial life. Below the ocean floor, a variety of chemical reactions between seawater and rocks, taking place over a range of temperatures, creates a chemical bouillabaisse. These chemicals diffuse upward and become sources of energy and carbon that sustain a wide variety of microbes. The microbes have evolved to take advantage of specific conditions in particular niches. (Illustration by Jayne Doucette, © Woods Hole Oceanographic Institution)