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Classification: grouping of org. based on their
similarities
Taxonomy: branch of biology that groups org.
Aristotle: 1st recorded method (350 BC)
-2 groups
A. Plants- grouped by size
-small, medium, large
B. Animals-grouped based on where live
Linnaeus: 1700’s
-developed modern classification system
-based on physical characteristics
-Binomial nomenclature: 2-word naming system
-1st genus: group of closely related species
-2nd species: descriptive word for animal
-e.g. dog – Canis domesticus
-rules: genus capitalized,
must be underlined/ italicized
Why do we use scientific names?
-Language differences
-Avoid confusing/misleading names
Why is classification important?
-helps us know what species are (have been)
on Earth
-shows us how species are related
-helps identify characteristics of org. (helpful or
harmful)
-naming system helps avoid confusing names
(starfish)
-each species has only 1 name (bluegill/brim)
Taxa: classification groups
Begin with broad/general and get specific
Kingdom
Animalia
Phylum
Chordata
Class
Mammalia
Order
Primates
Family
Hominidae
Genus
Homo
Species
sapiens
How do we determine relationships
1. Compare structures of modern org. w/ those
found in fossils
Phylogeny: evolutionary history
e.g. all cats have retractable claws
2. Similarities in development
3. Biochemistry-DNA & amino acids
4. Behavior
There are currently 3 domains
1. Eubacteria (common bacteria)
2. Archaebacteria (bacteria that live in extreme
habitats)
3. Eukarya (eukaryotes)
Kingdoms
Fungus
Protists
Plants
Animals
Dichotomous Key: tool for identification
Cladogram: family tree created based on
evolutionary relationships