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• 2 words – capitalize the first letter of the first

word and lowercase everything else. • First word is Genus second word is species

Ursus maritimus

Examplesscientific name = genus + species

• Homo sapien• Canis familiarius• Felis domesticus• Drosophilia melanogaster

HumanDogCatFruit 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 LevelsExample: 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 Archaea1. Kingdom: Bacteria• unicellular• prokaryotic• cell wall contains a

special molecule called peptidoglycan.

2. Kingdom: Archaebacteria

•Live in extreme environments

•Cell wall lacks peptidoglycan

Domain Eukarya3. Kingdom Protista

• Eukaryotic organisms (most are one celled)• Shows the greatest variety of organisms• Photosynthetic or heterotrophic

Domain Eukarya4. Kingdom Fungi

• Absorptive heterotrophs – absorb nutrients through their bodies

• Feed on dead or decaying organic matter• Many are multicellular• Yeast is unicellular

Domain Eukarya5. Kingdom Plantae

• Multicellular• Autotrophs (do

photosynthesis)• Cellulose in cell wall

Domain Eukarya 6. Kingdom Animalia

• Multicellular• Heterotrophic• Eukaryotic• Invertebrates

and Vertebrates