The Tara Oceans expedition collected these small zooplanktonic animals in the Indian Ocean: a molluscan pteropod on the right, and 2 crustacean copepods. On the left is a fragment of... In five related reports in this issue of the journal Science, a multinational team of researchers who spent three and a half years sampling the ocean's sunlit upper layers aboard the schooner Tara unveil the first officially reported global analyses of the Tara Oceans consortium. Planktonic life in the ocean is far more diverse than scientists knew, these reports show. They provide new resources for cataloguing the ocean's numerous planktonic organisms, which -- though critical to life on Earth, providing half the oxygen generated annually through photosynthesis, for example -- have largely been uncharacterized. The reports also reveal how planktonic life is distributed and how planktonic species interact, and they suggest that these organisms' interactions, more so than environmental conditions, help explain their community structures.