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Kingdom Protista. General Introduction. Protists first appeared in the fossil records about 1.5 billion years ago Demonstrate an important evolutionary advancement, a membrane bound nucleus. Protist Introduction Continued. Contain organelles such as ribosomes, mitochondria, and lysosomes
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General Introduction • Protists first appeared in the fossil records about 1.5 billion years ago • Demonstrate an important evolutionary advancement, a membrane bound nucleus
Protist Introduction Continued • Contain organelles such as ribosomes, mitochondria, and lysosomes • These structures provide a more efficient method of using available nutrients • Members of the Kingdom Protista are the simplest of the eukaryotes
Reproduce sexually and asexually • Require an aquatic environment • Some move around and act like animals, others perform photosynthesis like plants, and still others seem to "think" they're fungi!
Why Are ProtistsImportant? • Autotrophic protists, like phytoplankton, produce a significant portion of the Earth’s oxygen • Play an important role in the carbon cycle • Important producers and consumers in food chains. • Act as a road map for evolution!
If you look at a drop of pond water under a microscope, all the "little creatures" you see swimming around areprotists.
Kindom Protista • The Kindom Protista has traditionally been referred to as the “junk drawer” kingdom because any eukaryote that is not classified as a green plant, fungus, or animal tends to get placed there. • Protists are microscopic and unicellular
All protists have a nucleus and are thereforeeukaryotic. • Protists are either plant-like, animal-like or fungus-like.
3 types of protists: • 1) Plant-like protists (algae) are autotrophs – they contain chloroplasts and make their own food. • 2) Animal-like protists (protozoans) areheterotrophs – they are not capable of making their own food • 3) Fungus-like protists (slime molds) are also heterotrophs – they are not capable of making their own food
Protozoansare animal-like protists(all are heterotrophs) • The wordprotozoameans "little animal." They are so named because many species behave like tiny animals—specifically, they hunt and gather other microbes as food. • 4 groups of protozoans: classified according to how they move.
Protozoans consist of 4 groups which are classified according to their type of locomotion. • Protozoans digest their food in stomach-like compartments called vacuoles <vac-you-ohls>. • Protozoans range in size from 5 to 500 µm (.005 -.500 mm) in diameter. They can be classified into three general groups based on how they move.
Group 1 is the Phylum Sarcodina. These are the amoebae <ah-me-bee> • Linnaeus named the organism “chaos, chaos” when he saw it for the first time • Amoebae ooze along by means of pseudopodia (false feet), engulfing food as they go.
Amoebae live in water or moist places. • They have a cell membrane but no cell wall.
Group 2 is thePhylum Mastigophora, also referred to as the flagellates. • Are generally the smallest of the protozoa and have one or more flagella • Flagellates use their flagella to move. • Some parasitic flagellates (Giardia, Cryptosporidia) can form cysts to spread from host-to-host through contaminated water
Group 3is thePhylum Ciliophora. These are also called the ciliates. These are generally the largest protozoa. • They are covered with hair-like projections called cilia and they eat the other two types of protozoa as well as bacteria. • Ciliates are found in every aquatic habitat. (example: Paramecium)
Group 4 is the Phylum Sporozoa; the last group of protozoans • These are exclusively parasitic and non-motile (lack a means of independent locomotion) • Dependent on host(s) for nutrition and movement. • Are characterized by a spore-like stage in their life cycle (Plasmodium vivax– text. p. 231; causes malaria)
Plant-like protistsare traditionally referred to asalgae. • Algae are eukaryotic autotrophs. • They, along with other eukaryotic autotrophs, form the foundation of Earth’s food chains. • They produce much of Earth’s oxygen.
There are three unicellular phyla of algae: • Phylum Euglenophyta (Euglena) • Phylum Chrysophyta (Diatoms) • Phylum Pyrrophyta (Dinoflagellates)
Members of first phylum of algae, Euglenophyta, are both plant-like and animal-like. • Euglena are autotrophs since they make food from sunlight. Are also… • Heterotrophs since they ingest food from surrounding water.
The second unicellular algae, Chrysophyta, are photosynthetic autotrophs. • They have shells of silica. • They make up a large portion of the world’s phytoplankton which is Earth’s largest provider of oxygen.
The third unicellular algae, Phylum Pyrrophyta, are a major component of marine phytoplankton. • Also called the “Dinoflagellates” • These algae have at least two flagella set at right angles to each other and thick cell walls made of cellulose plates. • Blooms of dinoflagellates cause “Red Tide.”
Fungus-like protists: • Phylum Gymnomycotaare heterotrophic decomposers • slime molds; organisms having a noncellular and multinucleate creeping vegetative phase and a propagative spore-producing stage • comprised of: Myxomycetesand Acrasiomycetes
Slime Molds • have traits like both fungi and animals. During good times, they live as independent, amoeba-like cells, dining on fungi and bacteria. • if conditions become uncomfortable—not enough food available, the temperature isn't right, etc.—individual cells gather together to form a single structure called a slug because it so closely resembles the animal you sometimes see gliding across sidewalks. • The slug oozes towards light.
