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 animal
without confusion
Scientist have identified over 2 million species but...
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
Genus species:
(Latin)
Ursus americanus
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 Canis group 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