Classification and Protista Why do Scientists Classify? Imagine a grocery store… How are they organized? What would happen if they were not organized? How is your life organized? Why do Scientists Classify? Almost 13 billion known species of organisms Need to keep organized! (Easier to study!) • Classification the grouping of information or objects based on similarities. Why do Scientists Classify? • Taxonomy is the science of grouping and naming organisms. Useful because: once classified, scientists will know a lot about an organism Early Classification Systems Aristotle (4th century B.C.) -observed animals -watched appearance, behavior, movement -fly, swim, and walk/crawl/run -observed similarities and differences -used differences to divide into smaller subgroups Linnaeus Carolus Linnaeus (1750s) -used observations as basis of his system -placed organisms based on observable features Devised naming system for organisms: Binomial Nomenclature Linnaeus Binomial Nomenclature- 2 part naming system -uses Latin words First name (genus); second name (species) Genus species Felis concolor Genus is capitalized; species is NOT. If you can’t italicize, underline the genus and species! Classification Today Species with similar evolutionary histories are classified more closely together. -when organisms share a common ancestor, they share an evolutionary history Levels of Classification -based on contributions of both Aristotle and Linnaeus There are 7 levels of classification. Remember the first letter of this sentence: King Philip Came Over For Good Spaghetti. 7 Levels of Classification Kingdom Phylum Class Order Family Genus Species broadest level most specific Levels of Classification Taxonomic Categories • Taxon- a named group of organisms – Taxa range from having broad diagnostic characteristic to having specific characteristics • Genus- is defined as a group of species that are closely related and share a common ancestor Taxonomic Categories • Family- is the next higher taxon, consisting of similar, related genera. – Ursidae family contains 9 species of bears Higher Taxa • Order- contains related families • Class- contains related orders – Bears belong to order carnivora and class mammalia Higher Taxa • Phylum or division- contains related classes • Kingdom- contains related phlya or divisions • Domain is the broadest of all taxa and contains one or more kingdoms • Bears are classified in phylum chordata, Kingom Animalia, and Domain Eukarya Using the Classification System Field guides help identify organisms. -they highlight differences between similar organisms (like trees) Taxonomic Key (AKA Dichotomous Key) -paired statements that describe the physical characteristics of different organisms Taxonomic Key • • • • • • • • • • 1. Fruits occur singly ....................................................... Go to 3 1' Fruits occur in clusters of two or more ......................... Go to 2 2. Fruits are round ....................................................... Grapes 2' Fruits are elongate ................................................... Bananas 3. Thick skin that separates easily from flesh .............Oranges 3' Thin skin that adheres to flesh .............................. Go to 4 4. More than one seed per fruit ............................ Apples 4' One seed per fruit ............................................ Go to 5 5. Skin covered with velvety hairs .................... Peaches 5' Skin smooth, without hairs ........................... Plums Domains • Broadest, most inclusive taxon • Three domains • Archaea and Eubacteria are unicellular prokaryotes (no nucleus or membrane-bound organelles) • Eukarya are more complex and have a nucleus and membranebound organelles 19 Archaea live in harsh environments and may represent the first cells to have evolved. Sewage treatment plants, thermal vents, etc. 20 Eubacteria, some of which cause human diseases, are present in almost all habitats on earth. Live in the intestines of animals Many bacteria are important environmentally and commercially. 21 Domain Eukarya is Divided into Kingdoms • • • • Protista (protozoans, algae…) Fungi (mushrooms, yeasts …) Plantae (multicellular plants) Animalia (multicellular animals) 22 Protista •Most are unicellular •Some are multicellular •Some are autotrophic, while others are heterotrophic 23 Fungi • Multicellular, except yeast • Absorptive heterotrophs (digest food outside their body & then absorb it) • Cell walls made of chitin 24 Plantae •Multicellular •Autotrophic •Absorb sunlight to make glucose – Photosynthesis •Cell walls made of cellulose 25 Animalia • Multicellular • Ingestive heterotrophs (consume food & digest it inside their bodies) • Feed on plants or animals 26 27 28 Similarities and Differences in the Protist Kingdom • • • • • All are eukaryotes (cells with nuclei). Live in moist surroundings. Unicellular or multicellular. Autotrophs, heterotrophs, or both. Some can move - others cannot. 3 categories of Protists: • Animal-like •Fungus-like •Plant-like Animal-like Protists (Protozoans) *Unicellular Heterotrophs *Four groups based on movement: those with flagella, cilia, pseudopods, and the ‘others’. Protozoans with Pseudopods • Pseudopods also called ‘false feet’ • Cell membrane pushes in one direction & the cytoplasm flows into the bulge. • This allows the protozoan to move, dragging the rest of the cell behind it. Pseudopod Movement EXAMPLE OF HOW PSEUDOPODS MOVE FLOW PUSH DRAG Pseudopods & Feeding They can form pseudopods to surround & trap food. Then form a food vacuole to break down food in the cytoplasm. Pseudopods • Reproduce by mitosis • Contractile vacuole - it collects extra H2O & expels it from cell • Thin cell membrane • No definite shape. • Example - Amoeba Protozoans with cilia • Cilia - hairlike structures - help organisms move, get food and sense environment. • Multicellular with 2 nuclei. • 1 nuclei controls everyday functions • 1 nuclei is for reproduction. • Reproduce by mitosis or conjugation. Ciliates • Oral groove lined with cilia moves H20 containing food into food vacuole at end of oral groove. • Food vacuole breaks down food and sends through cell. • Anal pore sends out waste. • Example of protozoan w/ cilia: paramecium. CONTRACTILE VACUOLE CILIA FOOD VACUOLE ORAL GROOVE FOOD VACUOLE ANAL PORE Protozoans with flagella • Organisms called zooflagellates • Use long whiplike part called flagella to move. • These usually live inside other organisms. Other Protozoans • Called sporozoans - parasites • Feed on cells & body fluids of hosts Sporozoans like Plasmodium (causes malaria) have more than 1 host: mosquitoes and then humans Examples of Animal-like Protista • • • • Cilates- move by cilia Sarcodines- pseudopods Sporozoans- spores Zooflagellate- Flagella Plantlike Protists • • • • Better known as algae Autotrophs Size: unicellular to very large Contain different pigments so they come in different colors. • Euglena: special type of algae -when there is no sunlight they become heterotrophic. • Plant-like protists are algae. • 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 – Phylum Bacillariophyta – Phylum Dinoflagellata • Members of first phylum of algae, Euglenophyta, are both plant-like and animal-like. • Euglena are autotrophs since they make food from sunlight and • Heterotrophs since they ingest food from surrounding water. • The second unicellular algae, Bacillariophyta, 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. DIATOMS • The third unicellular algae, Dinoflagellata, are a major component of marine phytoplankton. • 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.” • Multicellular algae are classified by color. • Rhodophyta are red seaweeds. • They are found in warm or cold marine environments along coast lines in deeper water. • They absorb green, violet, and blue light waves. These light waves are able to penetrate below 100 meters. • Phylum Phaeophyta is made up of the brown algae. • They are found in cool saltwater along rocky coasts. • Giant Kelp are the largest and most complex brown algae. They have hold fasts and air bladders. • The last of the multicellular algae are the green algae from the Phylum chlorophyta. • Most green algae are found in fresh water habitats. A Volvox is a hollow boll composed of hundreds of flagellated cells in a single layer. Chlamydomonas are actually unicellular and flagellated. Funguslike Protists • Like animals, they are heterotrophs • Like plants, they have cell walls • Reproduce by spores (tiny cells that can grow into a new organism) • Not in fungi kingdom because they can move at one point in their lives. • Example are water or slime molds. • Fungus-like protists, Myxomycota and Oomycota are decomposers. • Phylum Myxomycota are made up of plasmodial slime molds. • Phylum Oomycota is made up of water molds and downy molds.