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
arrangement of organisms into
orderly groups based on their
similarities
Classification is also known as
taxonomy
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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Early Taxonomists
•2000 years ago,
Aristotle was the
first taxonomist
Aristotle divided
organisms into
plants & animals
He subdivided
them by their
habitat ---land,
sea, or air dwellers
•
•
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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
•Binomial
nomenclature used
•Genus species
•Latin or Greek
•Italicized in print
•Capitalize genus,
but NOT species
•Underline when
Turdus migratorius
writing
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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Hierarchy-Taxonomic Groups
BROADEST TAXON
Domain
Kingdom
Phylum (Division – used for plants)
Class
Order
Family
Genus
Species
Most
Specific
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Delightful
King
Phil
Came
Over
For
Good
Soup!
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Domains
• Broadest, most inclusive taxon
• Three domains
• Archaea and Bacteria are
•
unicellular prokaryotes (no
nucleus or membrane-bound
organelles)
Eukarya are more complex and
have a nucleus and membranebound organelles
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ARCHAEA
• Kingdom - ARCHAEBACTERIA
• Cell type-prokaryote-lacks a nucleus
• Live in HARSH environments
• Found in:
–Sewage Treatment Plants
(Methanogens)
–Thermal or Volcanic Vents
(Thermophiles)
–Hot Springs or Geysers that are
acid
–Very salty water (Dead Sea;
Great Salt Lake) - Halophiles
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ARCHAEAN
• Cell walls without
peptidoglycan
• Unicellular
• Autotroph or heterotroph
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BACTERIA
• Kingdom - EUBACTERIA
• Some may cause DISEASE
• Found in ALL HABITATS except
harsh ones
• Important decomposers for
environment
• Commercially important in making
cottage cheese, yogurt,
buttermilk, etc.
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Live in the intestines of animals
• Prokaryote-lacks a nucleus
• Cell walls with peptydoglycanpolymer consisting of sugars and
amino acids that forms a mesh-like
layer outside the plasma
membrane
• Unicellular
• Autotroph or heterotroph
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Domain Eukarya is Divided
into Kingdoms
•Protista (protozoans,
algae…)
•Fungi (mushrooms, yeasts …)
•Plantae (multicellular plants)
•Animalia (multicellular
animals)
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Protista
•Most are
unicellular
•Some are
multicellular
•Some colonial
•Some are
autotrophic,
some
heterotrophic
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Protista
•Eukaryote
•Some cell walls
of cellulose
•Some
chloroplasts
•Amoebas and
Slime molds
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Fungi
• Multicellular,
except yeast
unicellular
Absorptive
heterotrophs
•
(digest food
outside their body
& then absorb it)
• Cell walls
made of chitin
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Fungi
• Eukaryote-has
a nucleus
• Examples:
Mushrooms and
yeasts
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Plantae
•Multicellular
•Some green algae
are unicellular
•chloroplasts
•Autotrophic
•Absorb sunlight
to make glucose –
Photosynthesisautotroph
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Plantae
•Cell walls made of
cellulose
•Eukaryote
•Mosses, ferns,
flowering plants
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• Multicellular
• Ingestive
•
Animalia
heterotrophs
(consume food
& digest it
inside their
bodies)
Feed on plants
or animals
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Animalia
• Eukaryote
• No cell wall or
chloroplasts
• Sponges,
worms,
insects, fish,
mammals
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Taxons
•Most genera contain a
number of similar species
•The genus Homo is an
exception (only contains
modern humans)
Classification is based on
evolutionary relationships
•
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Basis for Modern Taxonomy
•Homologous structures (same
structure, different
function)
Similar embryo development
Molecular Similarity in DNA,
RNA, or amino acid sequence
of Proteins
•
•
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Homologous Structures (BONES in the FORELIMBS) shows
Similarities in mammals.
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Cladogram
Diagram showing how organisms are related based on
shared, derived characteristics such as feathers,
hair, or scales
Phylogeny-study of how living things and extinct
organisms are related to one another
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Cladogram
Clade-a group of species that includes a single common
ancestor and all descendants of that ancestor
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Primate
Cladogram
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Dichotomous Keying
•Used to identify organisms
•Characteristics given in
pairs
•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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