ProtistsHandout 24

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What are protists?

✤ Protists are an interesting group of organisms because of the diversity of life that exists within them. So, how do we make one definition for so many different organisms?

✤ By definition a protist is a eukaryotic organism that is not a plant, animal, or fungi.

✤ Additionally, all protists live in a moist environment.

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Three Types of Protists

✤ All life is classified into kingdoms (bacteria, archaebacteria, animal, plant, fungi, and protist). Normally, organisms in a kingdom share common characteristics. However, because protists are so diverse, it is difficult to say they all share characteristics in common. Because of this, scientists are (or have) eliminating the protist kingdom and replacing it with smaller groups.

✤ Those groups are based on the kingdom the organisms most resemble. How is this decided? By how the organism obtains its energy.

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Protozoa

✤ Means “first animals.”

✤ Similar kingdom: Animal

✤ Common characteristics: Heterotrophs (eat for energy), move

✤ Examples: paramecium and amoebas

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Algae

✤ Similar kingdom: Plants

✤ Common characteristics: autotrophs (self energizing through photosynthesis), have chloroplasts or similar

✤ Examples: volvox, euglena, spirogyra

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Decomposers

✤ Similar kingdom: Fungi

✤ Common characteristics: Decompose for energy/nutrients

✤ Examples: slime molds, downy mildews

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