Classification

Classification

• Taxonomy: branch of biology that groups organisms based on the presence of similar characteristics

• Taxonomist: scientist who group and name organisms after studying differences in their physical characteristics

Benefits of Classification• Accurately and uniformly names

organisms

• Prevents misnomers– Jellyfish– Starfish

• Uses same language to name all organisms– Latin or sometimes Greek

Sea”horseSea”horse”??”??

History of Classification

• Aristotle (382-322 BC)– 1st to divide and

classify organisms– Based on where

organism spends most of its life (air, water, etc)

– Divided them into two groups•Plants: herbs, shrubs,

trees•Animals: land, air, water

History of Classification

• Based on Aristotle’s system, how would you classify the following?– Bats, birds, lizards, wolves, walrus,

dolphins, goldfish, sea urchins, horse, koala, frogs, stingrays, wasp

Land Air Water

History of Classification

• What are some problems with this form of classification??

– Some organisms are grouped together even though they don’t have much in common

– Some organisms do not fit easily into Aristotle’s system• Walrus???• Frog???

History of Classification

• Carolus Linnaeus (1707-1778)– Based on physical similarities

between organisms– Problem

•Organisms given misleading “common” names OR one species given more than one common name

– Solution•Use latin to assign an unchanging global

scientific name to identify a species•Binomial Nomenclature

Binomial Nomenclature

• “Two Names”• 1st name: the genus (uppercase)• 2nd name: a descriptive name

(lowercase)

• Helps scientists researching the same organism in different countries/languages!

Common Name:House Sparrow

(US) Gorrion (Spain) Musch (Hollond)

Hussparf (Sweden)

Scientific Name:Passer domesticus

Modern Taxonomy

• Groups organisms based on evolutionary relationships

• Based on similarities in – External/Internal Structure– Breeding Behavior– Geographical Distribution– Chromosome comparisons– Biochemistry

Modern Taxonomy• Provides a way to study relationships

among organisms –both living and extinct

• Start with broad categories with general characteristics and then subdivide organisms by looking at characteristics specific to different organisms

• The MORE similarities between 2 organisms = more closely related!!!

Organisms are Classified in a Hierarchy of Taxa

• Taxon = group of organisms

• Domain- Eukarya  Kingdom- Animalia     Phylum- Chordata        Subphylum- Vertebrata          Class- Mammalia              Order- Carnivora                  Family- Canidae                      Genus- Canis                         Species- Canis lupus                           Subspecies- Canis lupus familiaris

Taxonomy

• Mnemonic Device to remember taxon groups:

• Dumb King Phillip Came Over For Good Spaghetti

• Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species