Why Classify To place organisms in some systematic

Why Classify? • To place organisms in some systematic order

Taxonomy • The science of classifying organisms into groups

Classify To assign an organism to a particular group Identify To determine the group to which an organism belongs

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-1700 s • 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 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 “genusspecies” 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