Describe one way all students in
this class can be separated into
groups, or classified.
Aristotle (384BC-322BC) developed the first
classification system, which divided all known
organisms into two groups: PLANTS and
ANIMALS.
Aristotle then divided each
of these main groups
into 3 smaller groups.
Animal Subgroups:
Land, Water, Air
Plant Subgroups: Small,
Medium, Large
Scientists have identified more than 2.5 million different
organisms. And their job isn’t even close to being finished!
Some biologists estimate that there may be at least 7
million different kinds of organisms living in tropical rain
forests and in the depths of Earth’s oceans. No wonder
why we need to classify!
Classification • Grouping of
different types of
organisms based on
similar
characteristics
Taxonomy • Branch of biology that
deals with classification
of living things
Carolus Linnaeus (1707-1778) like
Aristotle, classified organisms
according to their traits. The
classification systems of both
Aristotle and Linnaeus started with
the same two groups: Plants and
Animals. Linnaeus called these
groups kingdoms. But, unlike
Aristotle, Linnaeus divided kingdom
into 5 levels. Organisms were
placed in these levels based on
traits, including similarities of body
parts , physical form such as size,
shape, and methods of getting food.
Classification
• Carolus Linnaeus
system used today
(1700’s)
• All organisms
are divided into
7 levels of
classification
•Largest group
Kingdom
•Very diverse
Phylum
Class
Order
Family
Genus
Smallest groups and
most closely related to
Species
each other
Kings
Play
Chess
On
Fine
Green
Stools
Species • One kind of organism that
can mate with each other
& produce fertile
offspring
Kingdom
Phylum
Phylum
Phylum
Phylum
Phylum
Phylum
Naming organisms
Before Linnaeus developed his naming system, plants and
animals were named by a series of Latin words that
described the physical appearance of the organism. This
was very confusing. For example, let’s look at the first
name of the honey bee.
Apis pubescens, thorace
subgriseo, abdomine fusco,
pedibus posticis glabris
utrinque margine ciliatus.
This means “fuzzy bee, light gray
middle, brown body, smooth hind
legs that have a small bag edged
with tiny hairs.” Linnaeus named it
Apis mellifera which means “honeybearing bee.”
• Method used to name
Binomial
organisms
Nomenclature
• Devised by Linnaeus
• 2 names
– Genus species
Humans = Homo sapiens
Kingdom
Animalia
Phylum
Chordata
Class
Mammal
Order
Primate
Family
Homoide
Genus
Homo
Species
sapiens
Kingdom
Phylum
Animalia
Cordata
Class
Order
Family
Genus
Species
Mammalia
Carnivora
Canidae
Canis
Lupus
(the wolf)
Canis lupus
Let’s summarize…
1. How are organisms classified in the classification
system used today?
2. Explain the difference between a kingdom and a
species.
3. Explain the method used for naming organisms.
4. In a dichotomous key, how many descriptive
statements are found in each step?
5. When starting a dichotomous key, which step do
you start with?
6. What do you do if the first statement is false?
Review:
1. Which of the following places the seven major
classification groups in order from largest to
smallest?
(1.) phylum, class, kingdom, order, family, genus, species
(2.) kingdom, phylum, class, order, family, genus, species
(3.) kingdom, phylum, order, family, class, genus, species
(4.) genus, species, class, order, kingdom, family, phylum
2. The scientific name for a lion is
Panthera Leo. The word Panthera tells
us the lion’s
(1.) kingdom
(2.) phylum
(3.) genus
(4.) species
3. Members of a population of gray
squirrels, Sciurus carolinensis, are
classified in the same species because
they
(1.) obtain their food in the same manner
(2.) produce enzymes by synthesis
(3.) can mate and produce fertile offspring
(4.) live in the same area
4. In today’s classification system, 2
organisms would be most closely
related if they were classified in the
same
(1.) kingdom
(2.) phylum
(3.)genus
(4.)species
5. Which classification category contains
the greatest number of different types
of organisms?
(1.) kingdom
(2.) phylum
(3.) genus
(4.) species
Dolphin  Tursiops truncatus
Raccoon  Procyon lotor
Fruit flyDrosophila melanogaster