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Biological Environment > Protozoa |
This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. |
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Eukaryotes could now get a great deal of energy which they could use in new ways. They could feed by pulling in sacs of membrane and so swallowing and digesting bacteria. Eukaryotes which ate bacteria are called protozoa, meaning first animals. One of these is a protozoan.
Reproduction was much more complex for eukaryotes than for bacteria. Mostly they still reproduced by dividing in two, but they evolved some machinery to make sure that each daughter cell got one copy of each chromosome and at least one mitochondrion. Later sexual reproduction evolved. Biologists classify protozoa as belonging to the Protista. The protozoa are single-celled Eukaryotes, mostly too small to be seen with the naked eye but visible in the average microscope. Although they are the simplest eukaryotes, they are still far more complex than bacteria. Protozoa are very diverse group, not closely related to one another. There are more than 65,000 known species, over half of which are fossils. They are found in almost all soil, all water and their spores fill the air. Every time you drink a cup of water you swallow millions of live protozoa! Many are symbionts of other organisms, and about one-third of the living species are parasites. |
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Biological Environment > Protozoa |
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