Discovering the Forgotten Kingdom Protista
Protists, like algae and mold, are sometimes overlooked for classroom study, but they are astonishing in their diversity and importance.
By Lynsey Peterson
When studying kingdoms in science, protists do not get enough attention. If you ask a student to name the kingdoms of organisms, protista are often forgotten. The protists are grouped together mainly because they do not fit into the other kingdoms. However, even though it can be somewhat of a catch-all kingdom, there is an amazing diversity of life found in protists. Algaes, slime molds, and many unicellular germs are all part of the Kingdom Protista. The protists are even thought to be the first eukaryotic organisms on Earth. As eukaryotes, they have the same types of membrane bound organelles in their cells as plants, animals, and fungi. In fact, there are many similarities between protists and the other eukaryotic kingdoms.
Because of these similarities, Protista is subdivided into three categories based on their method of obtaining energy. There are animal-like, plant-like, and fungus-like protists. The animal-like protists are called protozoans. Just like animals, protozoans are heterotrophs that obtain their energy through eating other organisms. These protists are unicellular and classified further based on their movement and feeding methods. They may move with flagella, cilia, or not at all. They may even move with cytoplasmic ‘feet’ called pseudopodia. The amoeba and paramecia are well-known members of the protozoans. Students enjoy the opportunity to view these organisms under microscopes. They are fascinating to watch. Students can experiment with drawing the protozoans and describing their movement.
Algae are another example of protists that are amazing to view under a microscope. These plant-like protists are also known as Protophyta. They conduct photosynthesis, just like plants do. Some of these algae are unicellular, such as Euglena, and diatoms. These unicellular algae are important as the base of many aquatic food chains. There are also colonial and multi-cellular protophyta, such as green, brown, and red algae. The different pigments used by the protists in photosynthesis give them their color and common names.
The final subgroup of Protista is fungus-like protists. These protists get their energy, just like fungi, from the decomposition of organisms. This group includes water molds, downy mildews, and a student favorite, the slime molds. These organisms look just like a pile of slime, vomit, or other yucky goo. But they move slowly around, and decompose leaf litter and other dead organisms. In addition to viewing these protists under microscopes, you can also take your students outside on a rainy or damp day to try to spot a slime mold or downy mildew.
Once students have observed the diversity of the kingdom Protista, I have them create a picture book that shows the organisms and describes their characteristics. Students also research several common examples of protists and their importance. In addition to the examples listed above, there are other amazing protists to research such as: Malaria and Giardia, red tides, and a type of water mold responsible for the Irish Potato Famine. These are all examples of things that can be caused by protozoa. After students research they should be quick to remember the awesome diversity of Kingdom Protista. Other sample lessons can help students study Protists:
Kingdom Protista Lesson Plans:
Students examine members of the protists kingdom to identify characteristics, then answer questions about the activity and discuss the results.
Students identify characteristics of fungi and protista, and complete a worksheet on how humans use them in their everyday lives.
In this lesson, students learn about the structures of protists and compare them with multi-cellular organisms. They then learn what is in a drop of water, and present their findings to younger children at an elementary school.