An Exception to the Rule: Deep-Ocean Ecosystems The bottom of the ocean off the coast of Ecuador is teeming with life. Scientists found large communities of worms, clams, crabs, mussels, and bar-
nacles living near thermal vents in the ocean floor. These deep-ocean communities exist in total
darkness, where photosynthesis cannot occur. So where do these organisms get their
energy? Bacteria, such as those pictured in Figure 4, live in some of these organisms and use hydrogen sulfide to make their own food.