Chapter 18Chapter 18Classification of Classification of

OrganismsOrganisms

Chapter 18Chapter 18Classification of Classification of

OrganismsOrganisms

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Why Classify Organisms

• What are the Names of these fish?

Categories of Biological Classification

Organisms are grouped into large categories that are divided into smaller more specific categories.

– Taxonomy – the science of naming and classifying organisms based on their characteristics and evolutionary history.

– Binomial nomenclature – two-word system for naming organisms developed by Carolus Linnaeus. The naming system consists of the genus name followed by a descriptive word.

Scientific Names• Genus – a taxonomic category

containing similar species.• Scientific name – universally

recognized two-word name for an organism, genus and species names. Quercus rubra (Red Oak)

Smaller Groups• Some taxonomists divide the

categories into more specific categories.

Varieties – division of species for Plants

Subspecies – division of species - Zoologists

Writing Scientific Names

• The genus name is capitalized and

• The species name is lowercase. • Both names are either italicized

or underlined. Quercus rubra (Red Oak)

Rules to Scientific Names• Consists of 2 Latin words or terms

created acording to the rules of Latin grammar.

• 2 different organisms can not have the same species name.– Similar organisms will share the

same genus– Species name is a descriptor word.

First System of Classification

• Linnaeus – developed a system of classification based on similar features.

– Very simple system with only a few categories.

– Building block for our modern system.

System of Classifying Organisms

• Seven Levels of Classification1. Kingdom Kings2. Phylum Play3. Class Chess4. Order Only5. Family For6. Genus Great7. Species Steaks

Recognition of Species• Biological Species – Organisms

with similar morphology and the ability to reproduce creating fully fertile offspring.

The Six kingdom System

• Archaebacteria • Eubacteria • Protista • Fungi • Plantae • Animalia

Archaebacteria• Unicellular prokaryotes with

distinctive cell membranes, some are autotrophic, they live in harsh climates.

Eubacteria• “True” bacteria, unicellular

prokaryotes, bacteria found in everyday life some are autotrophic.

Protista• Eukaryotic mostly single celled

some may be multicellular, lack specialized tissue.

Fungi• Heterotrophic unicellular and

multicellular eukaryotic organisms. Absorb nutrients rather than ingesting them. Molds and Mushrooms

Plantae• Multicellular plants, most are

autotrophic, few are parasitic.

Animalia• Eukaryotic multicellular

heterotrophic organisms.

Three-Domain System• Based off the comparison of rRnA: living things

fall into these three domains• Bacteria (eubacteria)• Archaea (archaebacteria)• Eukarya (eukayotes)

1. Protista2. Plantae3. Fungi4. Animalia