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5 E$ j# z1 B/ E3 pOVER Orbulina universa, a planktonic foraminifera captured live from surface waters off Santa Catalina Island, California. Symbiotic dinoflagellates inhabit the calcite spines (length ~2.5 millimeters) radiating out from a spherical calcite shell (diameter ~0.5 millimeters). After four weeks, the shells sink to the sea floor and become part of the deep-sea microfossil assemblage. The geochemical compositions of these fossils are used to reconstruct past changes in seawater chemistry (see page 818). Photo: Howard J. Spero, University of California, Davis # m% i) k+ V6 H6 {, O5 f e
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发表于 2012-2-17 13:27
发表于 2012-2-17 14:45
