Classification
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Species of Organisms
•There are 13 billion known
species of organisms
•This is only 5% of all
organisms that ever lived!!!!!
•New organisms are still being
found and identified
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What is Classification?
Classification is the grouping of
objects or information based
on similarities. (aka taxonomy)
Taxonomy is a branch of biology
that groups and names
organisms based on their
characteristics
Taxonomists are scientists that
identify & name organisms
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Benefits of Classifying
•organisms
Accurately & uniformly names
•starfish
Prevents misnomers such as
& jellyfish that aren't
really fish
Uses same language (Latin or
some Greek) for all names
•
Sea”horse”?
?
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Confusion in Using Different
Languages for Names
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Latin Names are Understood by
all Taxonomists
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History of Classification Systems:
-The way we classify organisms
changes as we gather information
about:
DNA/protein analysis
Embryology- study of an
organism’s early stage of life
Anatomy (body
parts)/morphology (form)
Phylogeny- evolutionary history
of an organism
•
•
•
•
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Early Taxonomists
•2000 years ago,
Aristotle was the first
taxonomist
Aristotle divided
organisms into 2 groups:
plants & animals
He subdivided them by
their habitat.
•
•
Plants
herbs shrubs trees
Animals
air
land
water
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Early Taxonomists
•John Ray, a
botanist, was
the first to
use Latin for
naming
His names
were very long
descriptions
telling
everything
about the plant
•
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Carolus Linnaeus
1707 – 1778
• 18th century
taxonomist
• Classified
•
organisms by
their structure
Developed
naming system
still used
today
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Carolus Linnaeus
•Called the “Father of
Taxonomy”
•Developed the modern
system of naming known
as binomial nomenclature
Two-word name (Genus &
species)
•
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Standardized Naming
Ex. Homo sapiens
Most names are in
Latin.
1st word= genus
(capitalized)
2nd word= species
(lower case)- usually
descriptive
Both words must be
italicized or underlined
(if handwritten).
•
•
•
Turdus migratorius
•
American Robin
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Binomial Nomenclature
Which TWO are more closely related?
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Rules for Naming Organisms
• The International Code for
•
•
Binomial Nomenclature contains
the rules for naming organisms
All names must be approved by
International Naming Congresses
(International Zoological
Congress)
This prevents duplicated names
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Classification Groups
• Taxon ( taxa-plural) is a
•
•
category into which related
organisms are placed
There is a hierarchy of groups
(taxa) from broadest to most
specific
Domain, Kingdom, Phylum, Class,
Order, Family, Genus, species
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Current System (with human classification):
• Domain (3) – group of similar kingdoms
(Eukarya)
• Kingdom (7) – group of similar phyla (Animalia)
• Phylum- group of similar classes (Chordata)
• Class- group of similar orders (Mammalia)
• Order- group of similar families (Primates)
• Family- group of similar genera (Hominidae)
• Genus- group of similar species (Homo)
• Species- a group of organisms that can
interbreed and produce fertile offspring in
nature (H. sapiens)
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Hierarchy-Taxonomic Groups
BROADEST TAXON
Domain
Kingdom
Phylum (Division – used for plants)
Class
Order
Family
Genus
Species
Most
Specific
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Binomial Nomenclature
Snowshoe hare
Lepus americanus
Black Bear
Ursus americanus
Which TWO are more closely related?
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Dumb
King
Phillip
Cried
Out
“For
Goodness
Sake!”
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Cladogram
Diagram showing how organisms are related
based on shared, derived characteristics
such as feathers, hair, or scales
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Phylogenetic Tree
Phylogenetic tree- diagram that shows an
organism’s evolutionary history
A
B
C
D
E
F
Which 2
organisms are
most related?
A&B or A&C
A&C or C&D
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Dichotomous Keys
•Used to identify organisms
•Identification key that
contatins pairs of
contrasting descriptions
Read both characteristics
and either go to another
set of characteristics OR
identify the organism
•
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Example of Dichotomous Key
1a
1b
2a
2b
3a
3b
4a
4b
Tentacles present – Go to 2
Tentacles absent – Go to 3
Eight Tentacles – Octopus
More than 8 tentacles – 3
Tentacles hang down – go to 4
Tentacles upright–Sea Anemone
Balloon-shaped body–Jellyfish
Body NOT balloon-shaped - 5
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Can you make your own
dichotomous key?
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