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Evolution and the Fossil Record One of the first criticisms levelled against Darwin's theory of evolution through natural selection was that many simple organisms have been observed to remain largely unchanged over long periods of geological time. |
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Introduction Protozoa are the most abundant animals in the world in terms of numbers and biomass. Their principal importance is as consumers of bacteria. |
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Protozoan classification Four major groups of protozoa are recognised and often given the status of phylum. Note, however, that in the animal kingdom proper (Metazoa ), phyla are distinguished on their different body plans and that no comparable body plans are found in Protozoa. |
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Protozoan diversity Over 60,000 species have been described although you can be sure this is only a fraction of the total number of protist life forms. |
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