Taxonomy:
The Classification of Organisms
Why Do We Classify?
• To group and name organisms
logically
• Why not use common names?
– Puma
– Cougar
– Mountain lion
– Panther
– What is it?
… Felis concolor
How Do We Classify?
• Three methods have been used:
– Traditional classification – groups
based on physical similarities
– Evolutionary classification – groups
based on evolutionary history
– Molecular classification – groups
based on similarities in DNA or RNA
Appendages Conical Shells Crustaceans Gastropod
Crab Barnacle Limpet Crab Barnacle Limpet
Molted
exoskeleton
Segmentation
Tiny free-
swimming larva
TRADITIONAL EVOLUTIONARY
CLASSIFICATION CLASSIFICATION
The Taxonomic Categories
• Domain … Eukarya
• Kingdom … Animalia
• Phylum … Chordata
• Class … Mammalia
• Order … Carnivora
• Family … Ursidae
• Genus (genera) … Ursus
• Species … Ursus arctos
Taxon = each level of organization
Grizzly Black Giant Red Abert Coral Sea
bear bear panda fox squirrel snake star
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
Which is the most
ORDER Carnivora
inclusive taxon? FAMILY Ursidae
Which is the least GENUS Ursus
inclusive taxon? SPECIES Ursus arctos
The Domains & Kingdoms
DOMAIN
ARCHAEA
DOMAIN
EUKARYA
Kingdoms
Eubacteria
Archaebacteria
DOMAIN
Protista
BACTERIA
Plantae
Fungi
Animalia
Figure 18-12, p. 459
Classification of Living Things
DOMAIN Bacteria Archaea Eukarya
KINGDOM Eubacteria Archaebacteria Protista Fungi Plantae Animalia
CELL TYPE Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Eukaryote
Cell walls with Cell walls Cell walls of Cell walls of Cell walls of No cell walls
CELL
peptidoglycan without cellulose in chitin cellulose; or chloroplasts
STRUCTURES
peptidoglycan some; some chloroplasts
have
chloroplasts
NUMBER OF
Unicellular Unicellular Most unicellular; Most Multicellular Multicellular
CELLS some colonial; multicellular;
some some
multicellular unicellular
MODE OF Autotroph or Autotroph or Autotroph or Heterotroph Autotroph Heterotroph
NUTRITION heterotroph heterotroph heterotroph
Streptococcus, Methanogens, Amoeba, Mushrooms, Mosses, ferns, Sponges,
EXAMPLES Escherichia coli halophiles Paramecium, yeasts flowering worms,
slime molds, plants insects, fishes,
giant kelp mammals
1. What is the main difference between the
domains Bacteria & Archaea?
2. Which domain includes only eukaryotes?
3. Which kingdom includes only organisms
without cell walls?
4. Which kingdom includes Amoeba and
Paramecium?
5. Which two kingdoms include heterotrophs?
6. Which kingdom includes halophiles (and
thermophiles)?
7. Which kingdom includes organisms that all
have chloroplasts?
Binomial Nomenclature
• Each species is assigned a two-part
name – its “scientific name”
– Genus (capitalized, can be
abbreviated by first letter)
– Species (not capitalized)
• Always written in italics
• Examples:
– Ursus arctos (grizzly bear)
– E. coli (a bacterium)
Review
1. The classification of organisms is called …
2. Why don’t scientists use common
names?
3. What type of classification is based on
genetic information?
4. List the eight taxonomic categories, from
most inclusive to least inclusive.
5. Name the two parts of a scientific name.
6. How are scientific names written?