Ch. 3 Classification
Taxonomy = branch of biology that deals w/ naming & classifying organisms.
200

–to group based on similarities
• Examples of classifying in everyday life…?
–easier to “find”
–show shared traits
–show relationships among living & extinct species

• What is a dichotomous key?
– a tool used for classification
• At each step, the user is given two choices (either/or).
– Each alternative leads to another question…
» until the item is identified.
• What are two ways to make a dichotomous key?
– branching “tree” diagram
– list format

• How are organisms classified?
– very broad characteristics  very specific
• Based on…?
– evolutionary relationships
– What is a group of organisms called?
• taxon (plural = taxa)
– How many taxa are there?
» 8 (Domain  species)
Domain

st
–Aristotle
• How did he classify organisms?
–2 taxa
» 1. plants (by type of stem)
» 2. animals (by environment in which they live)
According to Aristotle, which of these 3 animals would be classified more closely?

Beginning of Modern Classification
–Carolus Linnaeus
• How did he classify organisms?
–2 main groups = kingdoms
» plants
» animals
–Also used other taxa (groups) including:
» genus
~similar species
» species
~organisms w/ similar traits

Beginning of Modern Classification
• What is a species?
– group of organisms capable of mating with one another in nature to produce fertile offspring

Beginning of Modern Classification
– used binomial nomenclature
• 2 name system
– written: Genus species or Genus species
» Genus = 1st name, capitalized
» species = 2nd name, lower case & descriptive
– Ex. Common name Genus & species
» Humans Homo sapiens
» White Oak tree
» Red Oak tree
»
Bottlenose dolphin
Quercus alba
Quercus rubra
Tursiops truncatus

Beginning of Modern Classification
• Why don’t we use common names?
1. two organisms can have same common name, but not sci. name
2. scientific names rarely change
3. scientific names are written in same language around the world

• What do current classification systems reflect?
– relationships
• based on evolutionary ancestry
• Ex. According to the phylogenetic tree on the right, who are humans most closely related to?

• Can classification systems change?
– Yes.
• Why?
– With scientific advancements, we gain new data & learn more about organisms…

• Classification systems we’re going to discuss:
– 5 Kingdom system
• Monera, Protista, Fungi, Plantae, Animalia
– 6 Kingdom system
• Monera split into Archaebacteria & Eubacteria… other 4 kingdoms (Protista, Fungi, Plantae, Animalia) stay same
– 3 Domain system
• Archaea, Bacteria, Eukaryota (Eukarya)
– 4 kingdoms (Protista, Fungi, Plantae, Animalia) grouped in Eukaryota

• Trick to help you remember major classification groups in the domain system…
• Did  Domain
• Katy  Kingdom
• Perry  Phylum
• Come  Class
• Over  Order
• For  Family
• Good  Genus
• Sushi?
 species

• What is the relationship among the levels?
– from Domain down, each level has a new set of criteria that must be shared
DOMAIN Eukaryota
– Organisms that are more closely related  share…
• more levels

Once an organism shares a more specific taxon
(lower group) it MUST share the more unifying taxa (higher groups)
How many levels of classification do we share with dolphins?

• When using the 5 or 6
Kingdom system…
– Which group is largest & most inclusive?
• Kingdom
– Which is smallest & least inclusive?
• species

• When using the 3
Domain system…
– Which group is largest & most inclusive?
– domain
– Which group is smallest
& least inclusive?
– species
Domain
Domain
Eukaryota

• prokaryotic
• unicellular
• feeding
– heterotrophic or autotrophic
• other characteristics
– older, less complex bacteria
– live in extreme environments
• examples
– bacteria:
• in salt lakes
• at hydrothermal vents

Domain: Bacteria
6 Kingdom system: Eubacteria
5 Kingdom system: Monera
• prokaryotic
• unicellular
• feeding
– heterotrophic or autotrophic
• other characteristics
– modern, more complex bacteria
• evolved from Archaea
– most common & very diverse
– free-living or pathogenic
• examples
– Staphylococcus
– E. coli
– cyanobacteria
Staphylococcus cyanobacteria

• All are eukaryotic
• 4 of the 5 (or 6) kingdoms
– 1. Protista
– 2. Fungi
– 3. Plantae
– 4. Animalia

Domain: Eukaryota
1. Kingdom: Protista
• eukaryotic
• mostly unicellular
• feeding
– heterotrophic or autotrophic
• other characteristics
– can be plant-like, animallike, or fungus-like
• examples
– Amoeba
– Paramecium
– Euglena
– algae algae
Paramecium
Amoeba
Euglena

Domain: Eukaryota
2. Kingdom: Fungi
• eukaryotic
• multicellular***
• feeding
– heterotrophic
• digest food outside & absorb nutrients
• other characteristics
– cell walls made of chitin
– decomposers & parasites
• examples
– mushrooms
– molds
– yeast (*** unicellular)

Domain: Eukaryota
• eukaryotic
• multicellular
• feeding
– autotrophic
• photosynthesis
3. Kingdom: Plantae
• other characteristics
– cell walls made of cellulose
– produce oxygen
• examples
– mosses
– ferns
– grasses
– shrubs
– trees

Domain: Eukaryota
• eukaryotic
• multicellular
• feeding
– heterotrophic
4. Kingdom: Animalia
• examples
• other characteristics
– no cell wall
– invertebrates
• insects
• worms
• sponges
• corals
– vertebrates
• fish
• birds
• amphibians
• reptiles
• mammals

• http://www.brainpop.com/science/diversityoflife/classification/preview.weml
• http://anthro.palomar.edu/animal/default.htm
• http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/kingdoms.html
• http://www.nclark.net/Classification