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Introduction to Organisms

Author(s): Deanne Erdmann, MS

Ecological Importance of Protists

Protists form a broad base across the bottom of the food chain, and they supply approximately one-half of the world's oxygen (unicellular algae compose a large portion of the world's phytoplankton). Protists, along with bacteria and fungi, are responsible for decomposing and recycling nutrients.

Many protist are helpful. Euglena are used to help treat sewage because of their unique ability to switch from an autotrophic to a heterotrophic nutritional mode, helping to maintain oxygen levels in the balance. Another helpful protist is Trichonympha which lives in the digestive system of termites and produces cellulase, an enzyme that enables termites to digest wood.

Animal-like protists are responsible for diseases such as malaria, amoebic dysentery, toxoplasmosis, African Sleeping Sickness and Giardiasis in humans. Some protists dramatically have affected human history. Phytopthana infestans, a water mold, destroyed potato crops throughout Ireland in the 1840s, leading to the Great Potato Famine and the eventual migration of large numbers of people into the United States. 

Some protists have medicinal and industrial uses. Carrageenan, from algae, is used to produce a thickening agent in ice cream, pudding, and candy. Chemicals from algae are used to manufacture waxes, plastics, paints and lubricants. Other chemicals made from Protists are used in treatment of ulcers, high blood pressure, and arthritis.