Levels of Classification
Domain
Order
Kingdom
Phylum
Class
Family
Genus
Species
Classification
 Classification is the grouping of things based on similar
characteristics.
 Putting living things into groups makes it easier to study
them.
 Classification begins with a broad group that is divided into
more specific groups.
 Taxonomy is the study of how things are organized.
Levels of Classification
 Domain – highest level
 Contains the greatest number of organisms
 3 Domains:
 Bacteria
 Archae
 Eukarya
Domain Bacteria
 Prokaryotes – no defined nucleus
 Two basic types:
 Cyanobacteria – (blue green algae) thought to be
the first photosynthetic organism on Earth that
helped to put O2 in the atmosphere
 Heterotrophic bacteria- bacteria that get energy
from other organisms
Domain Archaebacteria
 Extremophiles
 Found in deep ocean vents – feed off of sulfur compounds –
chemosynthesis
 Halophiles – live in salty environments
 Thermophiles – live in hot area
 Methanogens – produce methane in anoxic conditions
Domain Eukarya
 Divided into 4 kingdoms (division of domain)
 Animalia (Animal)
 Plantae (Plant)
 Fungus
 Protist
How are organisms organized into
domains and kingdoms?
 Cell type
 Ability to make food
 Number of cells in body
Animals
 Eukaryote
 Heterotroph
 Multicellular
Plants
 Eukaryotes
 Autotrophs
 Multicellular
Fungi
 Eukaryotes
 Most are multicellular
 Some unicellular
 Heterotrophs – feed by absorbing nutrients from dead or
decaying organisms.
 Examples - mushrooms
Protists
 Any eukaryote that cannot be classified as an animal, plant,
or fungi.
 Some autotrophs / some heterotrophs
 Most unicellular (amoeba)
 Some multicellular (seaweed)
Classification Chart
Domain/
Kingdom
Bacteria
Archaea
Eukarya
Animals
Plants
Fungi
Protists
Cell Type
How it Obtains
Food
Number of
Cells
Special Info
Classification Chart
Domain/
Kingdom
Cell Type
How it Obtains
Food
Number of
Cells
Special Info
Bacteria
Prokaryote
Auto/heterotroph
unicellular
Archaea
Prokaryote
Auto/heterotroph
unicellular
Extreme
environments
Eukarya
Eukaryote
Animals
Eukaryote
Heterotrophs
Multicellular
Diverse
environments
Plants
Eukaryote
Autotrophs
Multicellular
Flowering &
non-flowering
Fungi
Eukaryote
Heterotrophs
Most are
multicellular
Absorb
nutrients
Protists
Eukaryote
Auto/heterotrophs Uni/multicellula Odds & ends
r
group
Why do biologists classify organisms?
 Classification makes it easier to study organisms
 Taxonomy – the study of how organisms are organized.
What are the levels of classification?
 Domain – broadest and contains the most different types of organisms.
 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species – most specific and contains only one specific organism
Classification of Paddlefish
 Domain: Eukarya
 Kingdom: Animalia
 Phylum: Chordata
 Class: Actinopterygii
 Order: Acipenseriformes
 Family: Polyodontidae
 Genus: Polyodon
 Species: spathula
Classification of Paddlefish
 Domain: Eukaryota
Polyodon spathula is classified in the Domain Eukaryota because it has
a true nucleus as well as membrane-bound organelles.
 Kingdom: Animalia
Polyodon spathula are eukaryotic multicellular organisms that are
heterotrophs. They are also motile (swim) and lack cell walls.
 Phylum: Chordata
These American Paddlefish have bilateral symmetry, segmented
bodies, three germ layers (ectoderm, endoderm and mesoderm), a
coelom, a complete digestive tract, and have the five unique
characteristics to the Chordates--notochord; dorsal, tubular nerve
chord; pharyngeal pouches, endostyle, and postanal tail.
Classification of Paddlefish
 Class: Actinopterygii
This particular class contains ray-finned fishes.
 Order: Acipenseriformes
This Order contains primitive bony fish that have a
cartilaginous skeleton, a rostrum (or snout), a ventrally
located mouth, and a heterocercal tail fin.
 Family: Polyodontidae
The Polyodontidae Family consists of freshwater fish that
have many fossil relatives. A distinctive feature in this Family
is their elongated rostrums.
Classification of Paddlefish
 Genus: Polyodon
Polyodon is Greek for 'many toothed' referring to their
hundreds of bony, comb-like protrusions along their gill arch
called gill rakers; these gill rakers are specially adapted to
help them filter feed for plankton.
 Species: Polyodon spathula (P. spathula)
The word spathula refers to the paddle-like shape of the
Paddlefish's rostrum.
Comparison of Classifications of
Different Organisms
Common Name
Spoonbill Catfish
Human
Bobcat
Domain
Eukarya
Eukarya
Eukarya
Kingdom
Animalia
Animalia
Animalia
Phylum
Chordata
Chordata
Chordata
Class
Actinopterogii
Mammalia
Mammalia
Order
Acipenseriformes
Primates
Carnivora
Family
Polydontidae
Hominidae
Felidae
Genus
Polyodon
Homo
Lynx
Species
Polyodon spathula Homo sapiens
Lynx rufus
Naming Organisms
 Carolus Linnaeus the naming system used today.
 Binomial nomenclature – each organism is given a unique, two-part
scientific name.
 First word in name is the genus. It’s capitalized.
 Second word in the name is the species. It is lowercase.
 When typed, it is italicized and when handwritten it is underlined.
 Sometimes the genus is written just using the first letter of the
genus. Example: Polyodon spathula is the same as P. spathula
Why use scientific names?
 Scientific names are not the same as common names.
 Common names for an organism may vary from region to
region, whereas scientific names, are always the same no
matter where you are.
Taxonomic Key
 A tool used to help identify an organism.
 Paired statements describe characteristics.
Identify An Apple