Classification I: Intro IB Biology Classifying Organisms The science of classifying organisms is called taxonomy The “father of modern taxonomy” was Carolus Linnaeus (Carl von Linné) Organisms are grouped into “taxa” based on their similarities to each other The Old System 5 Kingdom Classification System: – Monera: all prokaryotes – Protista: single-celled eukaryotes (protists) – Fungi: multi-cellular heterotrophic sessile eukaryotes – Plantae: multi-cellular autotrophic sessile eukaryotes – Animalia: multi-cellular heterotrophic motile eukaryotes The New System 3 Domain System: – Archaea: prokaryotes; extremophiles – Eubacteria: prokaryotes; true bacteria – Eukarya: eukaryotes Protista Fungi Plantae Animalia Under Domain and Kingdom Organisms are grouped into smaller and smaller groups all the way down to their species A species is the most specific grouping and includes only organisms that can interbreed with each other and produce fertile offspring To remember the grouping order – just remember: Classification Taxa Kingdom Phylum Class Order Family Genus Species Note: Scientific names are always written with the first letter of the genus capitalized, the first letter of the species lower-case, and the whole thing underlined in italics. Together, these make up a species’ scientific name Example: Ursus americanus Common Name: American Brown Bear Domain Archaea Formerly part of the kingdom monera Microbiologists who study bacteria determined that the DNA of these are much different from other, true bacteria Most Archaea live in extreme conditions (very hot, acidic/basic, sulfurous, etc) Domain Eubacteria Formerly a part of the kingdom monera Name means “true bacteria” These are the kind of bacteria likely to make us sick, live in our gut to help us digest food, or be used in the making of cheese Domain Eukarya Contains all of the eukaryotes (organisms with a nucleus in their cells) – Protista – Fungi – Plantae – Animalia Kingdom Protista Includes All Protists: – Eukaryotic – Unicellular Animal-Like Protists (protozoans) – Pseudopods, Ciliates, Flagellates – Examples: Amoeba, Paramecia, Giardia Plant-Like Protists (autotrophic) – Euglenoids, Dinoflagellates, Diatoms, Green/Red/Brown Algae Fungus-Like Protists – Examples: Water molds, slime molds Kingdom Protista Amoeba Paramecium Water Mold Euglena Giardia Slime Mold Dinoflagellates Green Algae Brown Algae Diatom Kingdom Fungi All eukaryotic, multicellular, heterotrophic, sessile organisms Includes: molds, mushrooms, rusts, lichens Mycorrhizal associations allow plants to absorb more water and nutrients from the soil Kingdom Plantae All eukaryotic, multicellular, autotrophic, sessile organisms Produce their own food from sunlight and carbon dioxide Common Phyla: – Bryophyta (mosses) – Pteridophyta (ferns) – Coniferophyta (conifers, like pine trees) – Angiospermophyta (angiosperms, like flowering plants Kingdom Plantae Bryophyte (Moss) Pteridophyte (Fern) Pteridophyte (Fern) Coniferophytes (Pine Trees) Angiosperm; Dicot Angiosperm; Monocot Kingdom Animalia All eukaryotic, multicellular, heterotrophic, motile (most) organisms Common Phyla: – Chordata (those with spinal chords) – Annelida (worms) – Mollusca (inc. clams, oysters, etc..) – Arthropoda (crustaceans, insects, spiders) – Porifera (sponges) – There are about 40 such Phyla Human Classification Domain Eukarya – Kingdom Animalia Phylum Chordata – Class Mammalia Order Primate Family Hominidae Genus Homo Species Sapien Dichotomous Keys Used to help identify unknown specimen Work by asking yes or no questions whose answers lead the reader to the correct taxa for the organism Simple Example: 1a. Organism has 4 legs Go to # 2 1b. Organism has more than 4 legs Go to # 20 2a. Organism has a tail Go to # 3 2b. Organism has no tail Go to # 35 3a. Organism has stripes Bengal Tiger 3b. Organism has no stripes African Lion Dichotomous Key Try this one: 1a. Organism walks on all 4 legs (quadruped) 2 1b. Organism walks on 2 legs (biped) 8 2a. Organism has visible fur 3 2b. Organism has no visible fur 20 3a. Organism lives in warm climates 7 3b. Organism lives in cold climates 4 4a. Organism has brown or black fur Ursus Americanus 4b. Organism has white fur Ursus Maritimus
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