In 1748, Swedish botanist and anatomist, Carl Linnaeus published his taxonomic classification of all the plants and the animals of that period time. His classification was not based on evolutionary relationship but simply on resemblances. He divided all known forms of life between the plant and animal kingdom.Then in 1969, Robert H. Whittaker introduced the 5 kingdom system: monera, protista, plantae, fungi and animalia. Whittaker’s system recognized two fundamentally different levels of cell organization; prokaryotic and eukaryotic and both are under the kingdom monera. Eukaryotic can be divided into unicellular and multicellular. Then he distinguished three kingdoms of multicellular eukaryotes based partly on the types of nutrition; plantae, fungi and animalia. Plants are autotrophs that mean they produce their own food by photosynthesis. Fungi and animals are heterotrophs, they cannot do their own food. Protista consists of all unicellular eukaryotes that did not fit the definition of plants, fungi and animals. Some of them are multicellular too.
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