Introduction to Classification
Taxonomy

Taxonomy: branch of biology dealing with
classification – grouping and naming
organisms based on different
characteristics

Field of Taxonomy is continuously
changing –more information is being
gathered
Why Classify?

To identify differences in
structure, functions,
development, and
evolutionary history of
organisms
 Over
½ of human proteins
are shared with other
organisms
 Generally the more closely
related the organism, the
more similar the DNA

To overcome language
barriers – allows people
to share information
world wide
History of Classification

Aristotle (~350 B.C.) –
developed first classification
system of grouping organisms.
 Not
grouped by similar structures
or evolutionary similarities
 Plants versus Animals

Carolus Linnaeus (1753 A.D.) –
devised current classification
system using binomial
nomenclature
 Showed
relationships and
structural similarities between
organisms
Binomial Nomenclature

2 word naming system
 First

word: Genus (group of similar species)
Always Capitalize
 Second
word: Species (often describes
characteristic of the organism)



Always lowercase
The scientific name is always in latin (no longer
used in conversation so it doesn’t change)
Scientific name should always be italicized or
underlined
Why not use common names?

Misleading
 starfish
 dragonfly

Confusing
 blue
jay, blue coat, corn
thief
 dog, perro, chien
Why not use common names?

Many common
names, but
they all have
only one
scientific
name! Pyrrhosoma nymphula
Cyanocitta cristata
Pisaster ochraceus
Broader Grouping of Organisms: (Taxa)








Domain – new category;
broadest; 3 domains are
recognized
Kingdom – currently 6 are
recognized
Phylum
Class
Order
Family
Genus
Species – most specific
Acronyms to
remember the order:
Dearest King Phillip
Came Over For
Good Spaghetti
Or
Darling Kids Prefer
Cheese Over Fresh
Green Spinach
Prokaryotes
Kingdom
Bacteria
Kingdom
Archaebacteria
Kingdom
Protist
Eukaryotes
Kingdom
Fungi
Kingdom
Plant
Kingdom
Animal
For a Human:
Domain…….Eukaraya
Kingdom…….Animalia
Phylum…….Chordata
Class…….Mammalia
Order…….Primate
Family…….Hominidae
Genus…….Homo
Species…….Sapien
Linnaeus named
humans Homo
sapiens
means “wise
man”
— perhaps in a
show of hope &
optimism
Kingdoms

Organisms in each Kingdom have similar
characteristics:
 1)
Cell type (Eukaryotic versus Prokaryotic)
 2) Body form (Unicellular vs multicellular)
 3) Method of obtaining food (Autotroph vs
heterotroph)
 4) Presence of complex organ systems
Working through the Taxa

Moving from kingdom down to
species:
 The
number of species decreases
with each level of taxa
 The amount of similarity increases
with each level of taxa
 What taxa would have a higher
quantity of species, family or genus?
 In which taxa would the species have
the most in common, order or class?
Organism
House cat
Red Fox
Wolf
Gopher
Fly
Kindgom
Animalia
Animalia
Animalia
Animalia
Animalia
Phylum
Chordata
Chordata
Chordata
Chordata
Arthropoda
Class
Mammalia
Mammalia
Mammalia
Mammalia
Insecta
Order
Carnivora
Carnivora
Carnivora
Rodentia
Diptera
Family
Felidae
Canidae
Canidae
Geomydiae Muscidae
Genus
Felis
Vulpes
Canis
Thomomys
Musco
Species
F.
V. Fulva
Domesticus
C. Lupus
T. Bottae
M.
domestica