Chapter 18
Classification
The diversity of life
Why is it necessary to classify?
• 1.5 million species on the
planet so all creatures must
be organized with a
universal system. We call
this taxonomy.
• Scientists cannot use
common names because
they change depending on
where you live.
For example: cougar,
panther, puma, mountain
lion all represent the same
animal. It has a scientific
name – Felis concolor
Scientific Names
• Carolus Linneaus – Swedish botanist who
began the modern naming system.
• Developed a two word naming system called
binomial nomenclature (latin)
• 2 name naming system
• Scientific names are
• Descriptive
• In Latin
Ursus maritimus
• 2 words – capitalize the first letter of the first
word and lowercase everything else.
• First word is Genus second word is species
Examples
scientific name = genus + species
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Homo sapien
Canis familiarius
Felis domesticus
Drosophilia melanogaster
Human
Dog
Cat
Fruit fly
Classification System
• We organize all life on
Earth into 9 levels. Each
level is called a taxon.
• Domain is the largest – 3
large groups (see below)
• Species is the smallest
Classification Levels
Example: Grizzly bear
Human Taxonomy Levels
Changing Number of Kingdoms
History of Kingdoms:
• 1700’s - 2 kingdoms –Plants and Animals
• 1800’s – 3 kingdoms – Plants, Animals, Protists
(pond water critters)
• 1950’s – 5 kingdoms – Monera (bacteria),
Protists, Fungi, Plants and Animals
• 1990’s – 6 kingdoms - Eubacteria,
Archaebacteria, Protists, Fungi, Plants and
Animals.
Section 18-3 Kingdoms and Domains
• Shown below are the three domains and
the 6 modern kingdoms we use today.
Domain: Bacteria and Archaea
1. Kingdom: Bacteria
• unicellular
• prokaryotic
• cell wall contains a
special molecule called
peptidoglycan.
2. Kingdom: Archaebacteria
•Live in extreme
environments
•Cell wall lacks
peptidoglycan
Domain Eukarya
3. Kingdom Protista
• Eukaryotic organisms (most are
one celled)
• Shows the greatest variety of organisms
• Photosynthetic or heterotrophic
Domain Eukarya
4. Kingdom Fungi
• Absorptive heterotrophs – absorb nutrients
through their bodies
• Feed on dead or decaying organic matter
• Many are multicellular
• Yeast is unicellular
Domain Eukarya
5. Kingdom Plantae
• Multicellular
• Autotrophs (do
photosynthesis)
• Cellulose in cell wall
Domain Eukarya
6. Kingdom Animalia
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Multicellular
Heterotrophic
Eukaryotic
Invertebrates
and Vertebrates