Classification
Chapter 17
1
Species of Organisms
• Almost 2 million species of
organisms have been described
• Thousands more are discovered each
year
• The total number of species ranges
from 5 to 30 million
• Biodiversity- the variety
of organisms
2
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
•Accurately
& uniformly names
organisms
•Prevents
misnomers such as
starfish & jellyfish that aren't
•
really fish
Uses same language for all
countries (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 &
analagous structures
•
•
Ex) land, sea, or air dwellers
7
Carolus Linnaeus
1707 – 1778
• 18th century taxonomist
• Classified organisms by
•
•
their form and structure
(morphology & homologous
structures)
Developed 7 levels of
classification
Developed naming system
still used today
8
Carolus Linnaeus
•Called the “Father of
Taxonomy”
•Developed the modern
system of naming known as
binomial nomenclature- twoword naming system
(scientific name)
9
Binomial nomenclature uses:
•Genus species
•Latin or Greek
•Italicized in print
•Capitalize genus,
but NOT species
•Underline when
Turdus migratorius
writing
American Robin
10
Binomial Nomenclature
11
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
Kingdom, Phylum, Class, Order,
Family, Genus, species
12
King
Phillip
Came
Over
For
Good
Spaghetti!
14
video
15
Two Modern Systems
Six Kingdom System
Three Domain System
16
The Six Kingdoms:
17
KingdomArchaebacteria
•The prefix archae - comes from the Greek
word "ANCIENT"
•Unicellular & Prokaryotic
•autotrophic & heterotrophic by
chemosynthesis
•Live in extreme environments
Sewage
treatment
plants, thermal
vents, etc.
18
Kingdom Eubacteria
•Cause human diseases, are
present in almost all
habitats on earth
•“true bacteria”
•Unicellular & prokaryotic
•Heterotopic & autotropic
by chemosynthesis or
photosynthesis
•Many are important
environmentally and
commercially.
E. Coli –Live in
the intestines of
animals
19
Kingdom Protista
“The odds and ends
kingdom”
Dumping ground of
organisms that don’t fit
into the other kingdoms
Eukaryotic
Unicellular or
Multicellular
Autotroph or
heterpotroph
Ex) Algae, Slime
molds, Diatoms, and
Protozoa
20
Kingdom Fungi
• Multicellular,
except yeast
• Absorptive
•
heterotrophs
(digest food
outside their body
& then absorb it)
Decomposers
Ex) yeast, mold,
mildew, &
mushrooms
21
Kingdom Plantae
•Multicellular
•Autotrophic
•Absorb sunlight
to make glucose –
Photosynthesis
Cell walls made of
cellulose
•
22
Kingdom Animalia
• Multicellular
• Ingestive
•
heterotrophs
(consume food
& digest it
inside their
bodies)
Feed on plants
or animals
23
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Domains
• Broadest, most inclusive taxon
• Came from phylogenetic analysis of
rRNA genes
Three domains:
1. Eubacteria: unicellular prokaryotes
2. Archaea: unicellular prokaryotes with
distinctive cell membranes and other
unique genetic properties
3. Eukarya are more complex and have a
nucleus and membrane-bound organelles
25
Domain Eukarya includes:
•Protista (protozoans,
algae…)
•Fungi (mushrooms, yeasts …)
•Plantae (multicellular plants)
•Animalia (multicellular
animals)
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Notebook Quiz
1. List the levels of classification from most
broad to most specific.
2. What type of organisms are found in the
kingdom Archaebacteria? Are they
unicellular or multicellular?
3. What 4 kingdoms are in the Domain
Eukarya?
4. What is the difference between an autotroph
and a heterotroph? Give an example of each.
5. Describe the proper way to write an
organisms scientific name.
28
Classification is based on
evolutionary relationships:
• Homologous structures (same
structure, different function)
• Similar embryo development
• Similarity in DNA, RNA, or amino
acid sequence of Proteins
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Homologous Structures show Similarities in mammals.
30
Similarities in Vertebrate
Embryos
31
• Phylogenetics- the analysis of the evolutionary
or ancestral relationships among a taxon (group).
• Phylogenetic diagram (tree)- a branching tree
that indicates how closely related species are.
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33
34
Cladogram
Diagram showing how organisms are related
based on shared, derived characteristics
such as feathers, hair, or scales
35
Primate
Cladogram
36
37
Let’s Create A Cladogram from the following:
Derived Characters
segmented
jaws
hair
placenta
multicellular
limbs
kangaroo
+
+
+
-
+
+
earthworm
+
-
-
-
+
-
amoeba
-
-
-
-
-
-
lizard
+
+
-
-
+
+
cat
+
+
+
+
+
+
sponge
-
-
-
-
+
-
salmon
+
+
-
-
+
-
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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
39
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
40