What Are Some Facts About Ocean Ecosystems?

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The ocean ecosystem, also known as the pelagic zone, is the largest collective ecosystem on Earth. Open waters have the greatest volume and depth of any living zone on the planet. The basis of ocean life is plankton, which are microscopic plants that move along ocean currents. Small animals such as krill eat plankton, and then progressively larger animals eat krill. Ocean ecosystems cover 70 percent of the Earth.