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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
Bacteria
Image courtesy of JPL/NASA

Pre-Cambrian Life

About 2.5 billion years ago (BYA), after the iron in the ocean was gone to form iron ore deposits, oxygen began collecting in the atmosphere. Life took advantage of this change and developed eukaryotic cells. These are cells in which the organelle are outside of the nucleus, and the nucleus has a separate and distinct place within the cell. Both heterotrophs (early animals) and autotrophs (early plants) adapted to the new cells.

In cells with a nucleus respiration and photosynthesis are more efficient, so the production of oxygen in the environment of the early Earth speeded up. That made it possible for respiration (for animals which breathe oxygen) to begin in simple organisms. The new life forms which came to be were single-celled organisms like protozoans, amoeba, etc, animals which we now classify as part of the, Protista Kingdom .

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The Spring 2010 issue of The Earth Scientist, focuses on the ocean, including articles on polar research, coral reefs, ocean acidification, and climate. Includes a gorgeous full color poster!

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