Classifying OrganismsClassifying Organisms

Why do Scientists Classify?Why do Scientists Classify?

Imagine a grocery store…Imagine a grocery store…

How are they organized?How are they organized?

What would happen if they were not What would happen if they were not organized?organized?

How is your life organized?How is your life organized?

Why do Scientists Classify?Why do Scientists Classify?

Almost 2 million kinds of organisms on Almost 2 million kinds of organisms on EarthEarth

Need to keep organized! (Easier to Need to keep organized! (Easier to study!)study!)

ClassificationClassification

= process of grouping things based on = process of grouping things based on their similaritiestheir similarities

Why do Scientists Classify?Why do Scientists Classify?

TaxonomyTaxonomy

=scientific study of how living things =scientific study of how living things are classifiedare classified

Useful because:Useful because:

once classified, scientists will know a once classified, scientists will know a lot about an organismlot about an organism

Early Classification SystemsEarly Classification Systems

Aristotle (4Aristotle (4thth century B.C.) century B.C.)

-observed animals-observed animals

-watched appearance, behavior, -watched appearance, behavior, movementmovement

-fly, swim, and walk/crawl/run-fly, swim, and walk/crawl/run

-observed similarities and differences-observed similarities and differences

-used differences to divide into -used differences to divide into smaller smaller subgroupssubgroups

LinnaeusLinnaeus

Carolus Linnaeus (1750s)Carolus Linnaeus (1750s)

-used observations as basis of his -used observations as basis of his systemsystem

-placed organisms based on -placed organisms based on observable featuresobservable features

Devised naming system for organisms:Devised naming system for organisms:

Binomial NomenclatureBinomial Nomenclature

LinnaeusLinnaeus

Binomial NomenclatureBinomial Nomenclature=2 part naming system=2 part naming system-uses Latin words-uses Latin words

Genus speciesGenus species Felis concolorFelis concolorGenus is capitalized; species is NOT.Genus is capitalized; species is NOT.If you can’t italicize, If you can’t italicize, underlineunderline the the

genus and species!genus and species!

Classification TodayClassification Today

Species with similar evolutionary Species with similar evolutionary histories are classified more closely histories are classified more closely together.together.

-when organisms share a common -when organisms share a common ancestor, they share an evolutionary ancestor, they share an evolutionary historyhistory

Levels of ClassificationLevels of Classification

-based on contributions of both Aristotle -based on contributions of both Aristotle and Linnaeusand Linnaeus

There are There are 77 levels of classification. levels of classification.

Remember the first letter of this Remember the first letter of this sentence:sentence:

KKing ing PPhilip hilip CCame ame OOver ver FFor or GGood ood SSpaghetti.paghetti.

7 Levels of Classification7 Levels of Classification

KKingdom ingdom broadest levelbroadest level

PPhylumhylum

CClasslass

OOrderrder

FFamilyamily

GGenus enus

SSpeciespecies most specificmost specific

Using the Classification Using the Classification SystemSystem

Field guides help identify organisms.Field guides help identify organisms.

-they highlight differences between -they highlight differences between similar organisms (like trees)similar organisms (like trees)

Taxonomic Key (AKA Dichotomous Key)Taxonomic Key (AKA Dichotomous Key)

-paired statements that describe the -paired statements that describe the physical characteristics of different physical characteristics of different organismsorganisms

Taxonomic KeyTaxonomic Key 1. Fruits occur singly ....................................................... Go 1. Fruits occur singly ....................................................... Go

to 3to 3 1' Fruits occur in clusters of two or more ......................... Go 1' Fruits occur in clusters of two or more ......................... Go

to 2to 2 2. Fruits are round ....................................................... 2. Fruits are round .......................................................

GrapesGrapes 2' Fruits are elongate ................................................... 2' Fruits are elongate ...................................................

BananasBananas 3. Thick skin that separates easily from 3. Thick skin that separates easily from

flesh .............Orangesflesh .............Oranges 3' Thin skin that adheres to flesh .............................. Go to 43' Thin skin that adheres to flesh .............................. Go to 4 4. More than one seed per fruit ............................ Apples4. More than one seed per fruit ............................ Apples 4' One seed per fruit ............................................ Go to 54' One seed per fruit ............................................ Go to 5 5. Skin covered with velvety hairs .................... Peaches5. Skin covered with velvety hairs .................... Peaches 5' Skin smooth, without hairs ........................... Plums5' Skin smooth, without hairs ........................... Plums