Classification Notes

Taxonomy: the science of classification

• Why do we need a system of classification?– Brings order– Logical means of naming organisms– Scientific names are understood globally

• Common names are regional, not specific, and misleading (puma, cougar, mountain lion are the same animal)

• (ringworm and mealworm are not worms)

Aristotle

• Divided organisms into 2 groups• Plants: classified them on the basis

of structure and size• Animals: divided them on the basis

of where they live

Polynomial System

• A series of additional descriptive names added to the genus name

• Example: the scientific name for a bee using the polynomial system: Apes pubescens, thorace subgriseo, abdomine fusco, pedibus posticis glabris utrinque margine ciliates

Carolus Linnaeus

• Swedish botanist who developed a classification system based on structural features.

Seven taxa:

• Kingdom (largest category)• Phylum• Class• Order• Family• Genus• Species (most specific)

Binomial Nomenclature

• 2 part naming system• Latin (language used)• Genus species (written in italics)• Genus: a noun; always capitalized;

may be abbreviated by using the first letter

Determining Relationship

• Structure• Biochemistry• Development• Phylogeny (evolutionary history)

Human Classification

• Kingdom: Animalia• Phylum: Chordata• Class: Mammalia• Order: Primata• Family: Hominidae• Genus: Homo• Species: sapiens

Our Current System

• Recently changed to 6 kingdoms• The prokaryotic kingdom (Monera)

was split into 2 kingdoms

The Six Kingdoms1. Eubacteria

• Prokaryotes (no nucleus)• Unicellular• Mainly heterotrophs• Reproduce through binary fission• Live in diverse environments• Ex: cyanobacteria, spirochetes

2. Archaebacteria

• Prokaryotes• Unicellular• Mainly heterotrophs• Suited to extreme environments• Ex: halophiles

3. Protista

• Eukaryotic (have a nucleus)• Unicellular• Protozoans (animal-like; heterotrophs)• Algae (plant-like; autotrophs)• Reproduce sexually or asexually• Live in moist habitats• Ex: amoeba, euglena, diatom

4. Fungi

• Eukaryotic• Mostly multicellular• Saprophytes: obtain nutrients through absorption• Reproduce sexually and asexually• Most live in terrestrial habitats• Ex: mushrooms, yeast, puffballs

5. Plantae

• Eukaryotic• Multicellular• Autotrophs• Most live in terrestrial habitats• Reproduce sexually and asexually• Ex: mosses, ferns, flowering plants

6. Animalia

• Eukaryotic• Multicellular• Heterotrophs• Live in terrestrial and aquatic environments• Most reproduce sexually• Ex: worm, starfish, frog, snake, bird, dog