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Protists Kingdom Protista is the most diverse of all the kingdoms. Are protists eukaryotes or prokaryotes? Protists Protists can be animal-like, plantlike, or funguslike. • Protists are eukaryotes that are not animals, plants, or fungi. Protists • Animal-like protists consume other organisms. – heterotrophs – single-celled Protists • Plantlike protists are photosynthetic. – single-celled, colonial, or multicellular – no roots, stems, or leaves Protists • Funguslike protists decompose dead organisms. – heterotrophs – can move, whereas fungi cannot Protists Protists are difficult to classify. • Protista is one kingdom in the domain Eukarya. Protists • Protist classification will likely change. Protists II. Animal-like Protists Animal-like protists are single-celled heterotrophs that can move. Protists Animal-like protists move in various ways. • Animal-like protists are often called protozoa. macronucleus contractile vacuole food vacuole oral groove micronucleus cilia Protists • Some protozoa move with flagella Protists • Some protists move with pseudopods. – change shape as they move – amoebas, for example Protists • Some protozoa move with cilia. – cilia help protists swim and capture food macronucleus contractile vacuole food vacuole oral groove micronucleus cilia Protists Paramecia have contractile vacuoles to expel excess water. To avoid an obstacle, they back up, and move away in an avoidance reaction. Protists Some animal-like protists cause disease. human liver sporozoites • Malaria is caused by Plasmodium and spread by mosquitoes. liver cells developed parasites red blood cells Malaria Infection Protists Trypanosoma causes African sleeping sickness Protists Giardia is contracted from contaminated water Protists Protozoa can be beneficial • One protozoan lives inside termites, digests wood. • Both species benefit, so this is called mutualism. Protists III. Plantlike Protists Algae are plantlike protists. Plantlike protists can be single-celled or multicellular. colony daughter colony Protists Daughter colonies leaving the mother colony. Protists A. Euglenoids are a large group of plantlike protists. – mostly photosynthetic, have one or two flagella pellicle contractile vacuole nucleus flagellum chloroplast eye spot Protists • Euglena moves toward the light, which is known as a positive phototropism. • Has a red eyespot, which is light sensitive Protists B. Dinoflagellates are marine plantlike protists. –may be bioluminescent – can cause red tide Dinoflagellates Protists Noctiluca scintillans Protists C. Diatoms are plantlike protists with shells. – shells made of silica – produce large amounts of oxygen Protists More diatoms Protists • Multicellular algae are classified by their pigments. – Green algae – Brown algae: kelp – Red algae Protists Red algae is used to make agar, food thickener, and medicine capsules. Can exist at greater depths than brown or green algae Protists Spirogyra : a type of green algae Green algae can be unicellular or multicellular Protists IV. Fungus-like protists • include slime molds and water molds • decomposers, like fungi • can move, like animals Protists Slime molds • Eukaryotic organisms: fungus-like and animal-like • Decomposers, can move Protists • 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
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