Taxonomy: Classifying Organisms

Why classify living things?

  • To help us organize all the species of living things we discover . . .
  • To give every species a name based on a standard method so scientists from different countries can talk about the same animalwithout confusion
  • Scientist have identified over 2 million speciesbut...
  • Scientist project that there are more likely 10 million species on Earth!!!!
  • (We just have not found them all yet.)

Why classify?

Need to keep organized! (Easier to study!)

Classification: process of grouping things based on their similarities

Classify -to group things according to similar/different features (structures) that they share

Taxonomy:

Study of how living things are classified: (grouping and naming of organisms)

Useful because:once classified, scientists will know a lot about an

Organism

Using Classification System: 2 tools

Field guides help identify organisms.

-they highlight differences between similar organisms. They use descriptions, such as the external characteristics.

Taxonomic Key (AKA Dichotomous Key)-paired statements that describe the physical characteristics of different organisms

Early Classification System:

Aristotle (4th century B.C)

  • He developed a system that classified organisms as either plants or animals.
  • observed animals appearance, behavior, movement: fly, swim, and walk/crawl/run
  • used differences to divide into smaller subgroups

Carolous Linnaeus: (1750)

Placed organisms based on similar features

Devised naming system for organisms:Binomial Nomenclature

Binomial Nomenclature:

2 name system (Latin)

Genus species:Ursusamericanus

Genus is capitalized; species is NOT.

Italicize or underline the genus and species!

Canis lupus is the scientific name for a gray wolf.

  • Genus consists of a group of closely related species
  • Other animals in the Canisgroup include dogs and coyotes
  • Species consists of animals that can mate and produce fertile offspring
  • Only grey wolves are known as lupus.
  • The species name is always lowercase

Species with similar evolutionary histories are classified more closely together.

When organisms share a common ancestor, they share an evolutionary history: Phylogeny

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.

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

How does it work?

  • There are 6 broad kingdoms
  • Each level gets more specific as fewer organisms fit into any one group

Kingdom:

  • Organisms are grouped into kingdoms based on several factors:
  • Presence of a nucleus
  • Unicellular or multi-cellular
  • How organisms get their food.

6 Kingdoms:

  • Eubacteria
  • Archaebacteria
  • Protists
  • Fungi
  • Plants
  • Animals
  • Within each Kingdom, species are further subdivided. For each Kingdom, there are 6 levels of further classifications called “TAXA.”
  • The Six “Taxa” from Largest Taxa to Smallest
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species

Monera: Now 2 separate Kingdoms:

1. Eubacteria

2. Archaebacteria

Prokaryote, Unicellular and heterotrophic Ex: Bacteria

Protista

Eukaryote, unicellular, Motile (cilia, Pseudopods, flagella) Ex: Euglena, paramecium, Amoeba

Fungi:

Eukaryote, sessile, Multicellular (except yeast) Ex: Mushroom, Yeast, Mold

Plant:

Eukaryote, Multicellular, Sessile, Autotroph, cell wall Ex: trees, moss, pine,

Animal

Multicellular, heterotrophic, No cell wall, motile, Eukaryote

Ex: sponge, hydra, earthworm, grasshopper, dogs