Classification of Living Things
REMEMBER
BIODIVERSITY
______________
total of all the living things in an
ecosystem
SPECIES
___________
population of organisms that share
similar characteristics and can breed
with each other
What is classification?
 Classification is the grouping of
living organisms according to
similar structures and functions.
WHY CLASSIFY?
Identifies and names organisms
Groups organisms in a logical manner
TAXONOMY
_______________ =
branch of biology that
names and groups organisms
Early classification systems
 Aristotle grouped animals
according to the way they
moved
Aristotle’s system
By: Riedell
PLANTS:
Based on
size of stem
ANIMALS:
Based on
where they lived
Image from: http://www4.d25.k12.id.us/ihil/images/Cougar.
Common names can vary
Example:
puma,
catamount,
mountain lion,
cougar
. . . are all names
for same animal
By using a universally accepted scientific name,
scientists can be sure they are discussing
the same organism
Common names can be misleading
Ex:
A jellyFISH isn’t a fish,
but a seaHORSE is!
Image from: http://en.wikipedia.org/wiki/Jellyfish
Sea cucumber
sounds like a plant
but… it’s an animal!
The modern classification
system :
Developed by Carolus Linnaeus
Consists of 7 levels:
 Kingdom
 Family
 Phylum
 Genus
 Class
 Species
 Order
Helpful way to remember the 7
levels
 King Philip Came Over For
Grape Soda.
 King Philip Came Over For
Green Skittles.
Binomial Nomenclature
 Developed by Carolus Linnaeus

Scientists agreed to use ____________ to give
a single name to each species.
 Two-name system:
• First name is the organism’s
genus
• Second name is the organism’s
species
What rules are used to write
scientific names?
The first letter of the genus is ALWAYS
capitalized
 The first letter of the species is NEVER
capitalized
 Scientific names of organisms are
always italicized or underlined

GENUS = group of closely related
species
GENUS = Ursus (Includes many kinds of bears
Ursus
arctos
Ursus
maritimus
Ursus
americanis
SPECIES = unique to each kind of bear
http://www.macecanada.com/images/bears/kodiak_bear.gif
http://students.cs.byu.edu/~tole/Virtual%20Zoo/polar-bear.jpg
http://en.wikipedia.org/wiki/Image:Black_bear_large.jpg
Using the Classification System
Field guides help identify organisms.
-they highlight differences between similar
organisms (like trees)
Taxonomic Key (Dichotomous Key)
-paired statements that describe the
physical characteristics of different
organisms
Taxonomic Key
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








1a Fruits occur singly ....................................................... Go to 3
1b Fruits occur in clusters of two or more ......................... Go to 2
2a Fruits are round ....................................................... Grapes
2b Fruits are elongate ................................................... Bananas
3a Thick skin that separates easily from flesh .............Oranges
3b Thin skin that adheres to flesh .............................. Go to 4
4a More than one seed per fruit ............................ Apples
4b One seed per fruit ............................................ Go to 5
5a Skin covered with velvety hairs .................... Peaches
5b Skin smooth, without hairs ........................... Plums
What steps would you use to identify a peach?
Eubacteria
prokaryotic
unicellular
Archaebacteria
prokaryotic
unicellular
Protista
eukaryotic
most unicellular
Fungus
eukaryotic
most multicellular
Plant
eukaryotic
multicellular
Animal
eukaryotic
multicellular
cell
cell
most cell
most tissue
systems
systems
Cell Wall
peptidoglycan
contains
uncommon lipids
pectin or none
(green algae:
cellulose)
chitin
cellulose
none
Mode of
Nutrition
auto/heterotroph
auto/heterotroph
auto/heterotroph
heterotroph
(absorption)
autotroph
heterotroph
asexual
some motile
asexual
nonmotile
sexual/asexual
motile/nonmotile
sexual/asexual
most nonmotile
sexual/asexual
nonmotile
sexual/asexual
motile
aid in digestion
many pathogenic
(malaria, African
sleeping sickness,
amoebic
dysentery)
cellulose digestion
many pathogenic
(athlete’s foot,
yeast infection,
ringworm)
lichen
epiphyte
mycorrhizae
mistletoe
parasitic worms,
barnacles,
clownfish
decomposers
major oxygen &
food source
(photosynthesis trophic level 1)
human impact on
environment
fermented food
products
food source
antibiotics
can’t live without
‘em
medicine source
invertebrates
vertebrates
Cell Type
Number of Cells
Level of
Organization
Reproduction
Motility
Symbiotic
Relationship
fix nitrogen
many pathogenic
aid in human
digestion
Ecological
Importance
fix nitrogen
decomposers
decomposers
algae major
aquatic oxygen &
food producers
algal bloom
gave rise to
eukaryote
organelles
can live in
extreme
conditions
ancestors of
eukaryotes
toothpaste teeth
whiteners
Other
sponges
Examples
Escherichia coli
Streptococcus
methanobacteria
algae, diatoms,
amoebas,
lichen, yeast,
mushrooms
trees
flowers
grass
mammals
Making a dichotomous key


Separate into two distinct groups
Now only work on one of the groups!
• Separate that group into two groups and so on
and so on until you come up with just one thing
described.

Once you finish that grouping start on the
other group that you made in the beginning.