Classification of Living Things

Chapter 18

Why Classify

• Biologists have classified and named over 1.5 million species– Estimate that 2 million- 100 million have yet to be

discovered• Classification is used to name organisms and

group them in a logical manner

Taxonomy• A branch of biology where scientists classify

organisms and assign each a universally accepted name

Taxonomy

• A good classification system puts organisms in groups with other organisms that are similar

• With out discussion; draw what comes to mind when you hear the word: cat

Use of common names

• Common names vary among languages and even regions in the same country

–Mountain lion–Puma–Cougar–Panther

Use of common names

• Different species sometimes share a common name– What is a buzzard???

United States-Vulture

United Kingdom (England)-Hawk

Removing confusion

• To avoid confusion scientists refer to organisms by their scientific name

Aegypius monachus Buteo jamaicensis

Use of common names

• Common names can be misleading

jellyFISHseaHORSE

Sea cucumber

Naming System

• Carolus Linnaeus– Developed a two word naming system

• Before Linnaeus scientists used detailed physical descriptions – Names were long and confusing

• Binomial Nomenclature– Each species is assigned a two-part scientific name

Hierarchical system (consists of levels)Each level is a taxon

Taxonomic Nomenclature

KingdomPhylum

ClassOrderFamilyGenus

Species

Kids PreferCandyOverFried

Green Spinach

Kingdom- AnimaliaPhylum- Chordata

Class- MammaliaOrder- Carnivora

Family- FelidaeGenus- Panthera

Species- leo

Binomial Nomenclature

Rules to follow1. Always written in italics (or underlined)2. First word is capitalized3. First word is the genus4. Second word is lowercased5. Second word is the species

Binomial Nomenclature

• Genus a group of closely related speciesUrsus

Binomial Nomenclature

• Species a group of similar organisms that can breed

and produce fertile offspring

Ursus Ursus Ursusarctos maritimus americanis