Chapter 9 The Classification of Organisms
Why Classify? To place organisms in some systematic order
Taxonomy The science of classifying organisms into groups
To assign an organism to a particular group Classify To assign an organism to a particular group Identify To determine the group to which an organism belongs
The Classification Hierarchy
Aristotle Based his groupings on appearance Artificial classification system His system was used for almost 2,000 years.
Carolus Linnaeus Designed a new classification system in the mid-1700s His system was based on observable characteristics but was more developed and adaptable.
Today’s System of Classification Start with the broadest group or classification and work down to the most specific category.
Kingdom Phylum Class Order Family Genus Species
Rules for the Hierarchy Each group can be divided into several groups on the next level. Each group has characteristics that all levels under the group possess. Each level can be subdivided before reaching the next level.
Kingdom Archaebacteria Kingdom Eubacteria Kingdom Archaebacteria Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia
The Kingdom Eubacteria Prokaryotic cells Cell walls contain peptidoglycans. Most abundant organisms on the earth
The Kingdom Archaebacteria Prokaryotic cells Cell walls do not contain peptidoglycans. “Extremophiles”
The Kingdom Protista Eukaryotic cells Unicellular or colonial Protozoans and algae
The Kingdom Fungi Eukaryotic cells Unicellular or colonial (lack tissues) All are heterotrophic. Examples: molds, yeasts, and mushrooms
The Kingdom Plantae Eukaryotic cells Multicellular with tissues Most are autotrophic. Examples: trees, ferns, flowers, grains
The Kingdom Animalia Eukaryotic cells Multicellular with tissues All are heterotrophic. Examples: worms, sponges, insects, vertebrates
Scientific Names Binomial nomenclature “Two-name” naming system proposed by Linnaeus System of naming organisms in which each organism is given a genus name and a species name
Scientific Names Binomial nomenclature Gives organisms a “genus-species” name
Using Scientific Names Example: Canis familiaris “Canis” (Genus: capitalized) “familiaris” (Species: not capitalized) Both names are underlined or italicized.
Why Latin? Dead language Known by scholars Highly descriptive
Species A population of organisms Structurally similar but with a degree of variation Can interbreed and produce fertile offspring