Classification
Chapter 17
1
Species of Organisms 17-1
•There are 13 billion known
species of organisms
•1.75 million have been named
and described by scientists.
•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
3
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”??
4
Confusion in Using Different
Languages for Names
5
Latin Names are Understood by
all Taxonomists
6
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)
•
10
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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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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Daring
King
Phillip
Came
Over
For
Gooseberry
Soup!
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16
Taxons 17-2
•Most genera contain a
number of similar species
•The genus Homo is an
exception (only contains
modern humans)
Classification is based on
evolutionary relationships
•
17
Determining Species
• Typological Species Concept
–Looks at physical characteristics
–Limited due to variation of alleles for traits
• Biological Species Concept
–Looks at similarity in characteristics and the ability to
breed fertile offspring
–Limited due to not all separate species are unable to
breed (i.e. wolves and dogs)
• Phylogenetic Species Concept
–Looks at evolutionary history
–Limited due to unknown histories for some species
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Basis for Modern Taxonomy
•Homologous (morphological
characters) structures (same
structure, different
function)
Similar embryo development
Molecular Similarity
(biochemical characters) in
DNA, RNA, or amino acid
sequences in Proteins
•
•
19
Homologous Structures (BONES in the FORELIMBS) shows
Similarities in mammals.
20
Similarities in Vertebrate
Embryos
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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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• As animals evolve, they derive new features, or
characteristics.
• A derived characteristic can be any attribute of an
animal, from the shape of its bones and muscles
to its genetic chemistry and DNA.
+/- Table
0/1
Table
Cladogram
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 6
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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1. a. wings covered by an exoskeleton ………go to step 2
b. wings not covered by an exoskeleton ……….go to step
3
2. a. body has a round shape ……….
Coccinella septempunctata
b. body has an elongated shape ………. Camnula
pellucida
3. a. wings point out from the side of the body ……….
Aeshna cyanea
b. wings point to the posterior of the body ……….
Musca domestica
Making a Dichotomous Key
• Tree
• Dichotomous Key
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Domains 17-3
• Broadest, most inclusive taxon
• Three domains
• Archaea and Eubacteria are
•
unicellular prokaryotes (no
nucleus or membrane-bound
organelles)
Eukarya are more complex and
have a nucleus and membranebound organelles
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3 Domains
The Six Kingdoms
Animalia
Plantae
Protista
Eubacteria
Archaebacteria
Ancient common ancestor
Fungi
ARCHAEA
• Probably the 1 cells to evolve
• Live in HARSH environments
• Found in:
st
–Sewage Treatment Plants
–Thermal or Volcanic Vents
–Hot Springs or Geysers that are
acid
–Very salty water (Dead Sea;
Great Salt Lake)
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ARCHAEAN
34
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
36
Domain Eukarya is Divided
into Kingdoms
•Protista (protozoans,
algae…)
•Fungi (mushrooms, yeasts …)
•Plantae (multicellular plants)
•Animalia (multicellular
animals)
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•Most are
unicellular
•Some are
multicellular
•Some are
Protista
autotrophic, while
others are
heterotrophic
Mostly Aquatic
•
38
Fungi
• Multicellular,
except yeast
• Absorptive
•
heterotrophs
(digest food
outside their
body & then
absorb it)
Cell walls
made of chitin
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Plantae
•Multicellular
•Autotrophic
•Absorb sunlight
to make glucose –
Photosynthesis
Cell walls made of
cellulose
•
40
• Multicellular
• Ingestive
•
Animalia
heterotrophs
(consume food
& digest it
inside their
bodies)
Feed on plants
or animals
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Classification is Fun! 
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