KEY CONCEPT Kingdom Protista is the most diverse of all the kingdoms.

1. KEY CONCEPT Kingdom Protista is the most diverse of all the kingdoms. Figure: Although they are both protists, the round Didinium hunts live paramecia almost exclusively. It captures, paralyzes, and reels in paramecia like fish on a line. (colored SEM; magnification 2000 X)

2. Protists are eukaryotes that are not animals, plants, or fungi. Protists can be animal-like, plant-like, or fungus-like. Figure: Didinium is a specialist that eats only paramecia. When no paramecia are around, Didinium just turns into a cyst and waits until more come along. Paramecia are considered generalists, because they will eat anything smaller than themselves.

3. Animal-like protists consume other organisms. They are often called protozoa. macronucleus contractile vacuole food vacuole oral groove micronucleus cilia • heterotrophs • single-celled Fig. Zooflagellates (below) have flagella that help them move through water. (colored SEM; magnification unknown) Fig. A paramecium (above) is a single-celled protist covered with thousands of cilia that are used to swim and capture food. Its organelles can be identified through its transparent cell membrane. (colored SEM; magnification 400 X)

4. Some animal-like protists move with pseudopods. • change shape as they move • amoebas Fig. Feeding Habits of an Amoeba Amoebas feed by engulfing food.

5. Plant-like protists are photosynthetic. • single-celled, colonial, or multicellular • no roots, stems, or leaves Figure: Pediastrum are algae that live in colonies. Like plants, they use sunlight to make food. (colored SEM; magnification unknown) Figure: Giant kelp are a type of brown algae that form underwater forests. The forests are home to a large variety of marine organisms.

6. colony daughter colony Plant-like protists can be single-celled or multicellular. • Photosynthetic plant-like protists are called algae. Fig. Volvox are actually hundreds of individual algae cells that join together to form a colony in the shape of a hollow ball. Offspring form smaller daughter colonies inside the parent colony. (LM; magnification 50 X)

7. have two flagella • may be bioluminescent, can produce light internally through chemical reactions. • can cause red tide due to toxins they produce. • Dinoflagellates are mostly marine plant-like protists. Dinoflagellates

8. Diatoms are plant-like protists with glasslike shells. • shells made of silica • produce large amounts of oxygen Fig. Diatoms are known for their delicate glasslike cell walls, or shells, that can have many shapes. They are common in both freshwater and marine environments. (colored SEM; magnification unknown)

9. Fungus-like protists decompose dead organisms. • heterotrophs • can move, whereas fungi cannot • Fig. Slime molds have both fungus-like and animal-like traits. • decomposers, like fungi • can move, like animals

10. Water molds are freshwater, fungus-like protists. • one type of water mold caused Great Potato Famine of Ireland in the 1800’s • made of branching strands of cells • can be parasites of plants or fish Fig. The water mold Phytophthora infestans causes disease, including potato blight in many plants. This disease was the cause of a seven-year famine in Ireland in the 1800s. (colored SEM; magnification 100 X)

11. Protists are difficult to classify. • Protista is one kingdom in the domain Eukarya.

12. Protist classification will likely change. • Some protists are not closely related. • Molecular evidence supports reclassification.