Reference Text:
Modern Biology
Chapter 18 – Section 1
Pgs. 336 - 341
• All Organisms on earth
are said to have descended
from an ancient common
ancestor.
WHAT THINGS DO WE CLASSIFY?
WHY DO WE CLASSIFY THEM?
Every Year, thousands of new species
are discovered.
To study so many life-forms, biologists
organize or classify them into numerous
groups based on similar characteristics
(structures).
Biological Classification: to group things according to
similar/different structures that they share.
Classification is very useful in Biology…
• Indicates relationships between species
• Accurately & uniformly names organisms; star
fish and jelly fish aren't’ really fish
TAXONOMY:
The branch of biology that classifies organisms according
to their characteristics and
evolutionary history
TAXONOMISTS:
• scientists that identify & name organisms.
• named
organisms in a way that reflects their
classification.
• use
the same language (Latin or some Greek) for all
names.
The first classification
system was developed
2000 years ago by Greek
Philosopher, Aristotle.
He was the first
taxonomist.
•
•He simply divided organisms into
plants & animals
•He then subdivided them by
their habitat:
•land, sea, or air dwellers
•Plants, by stem structure
As modern science developed
and more & more organisms
began to be discovered,
Biologists realized Aristotle’s
system was no longer
adequate for naming &
organizing all life on earth.
Sea”horse”??
European bee: Apis pubescens, thorace
subgriseo, abdomine fusco, pedibus
posticis glabris utrinque margine ciliatis.
Linnaeus’s System
In response to the need
for better organization,
an 18th century Swedish
botanist named Carolus
Linnaeus offered a
solution to the confusion
of classifying and naming
organisms.
Carolus Linnaeus
1707 – 1778
• Created
a hierarchical
system for classifying
•
organisms
Developed naming
system still used today
The “Father of
Taxonomy”
Linnaeus’s System
Linnaeus classified organisms into nested
Levels of Classification based on similarities in
morphology (form & structure), rather than by
location.
For example, although
Bats can fly, he classified
them as mammals, not
birds, because they share
common traits with other
mammals; they have hair,
have live births and nurse
their offspring with milk.
Linnaeus’s System
The Linnaeus System of Taxonomy uses a hierarchical system
for classifying organisms from broadest to most specific.
The Seven Levels of Classification!
Kingdom
Phylum
Class
Order
Family
Genus
Species
BROADEST TAXON
Each category or level is called
a taxa, hence the name
taxonomy!
MOST SPECIFIC
Linnaeus’s System
Levels of Classification!
The Nested Nature of Biological Classification
Levels of Classification
Keep
Plates
Clean
Or
Family
Gets
Sick
Taxonomic Classification
Taxonomic Group:
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
Name: Genus &
species
tiger
Animal
Chordates
Mammals
Carnivores
Felines
Panthera
tigris
grey wolf
Animal
Chordates
Mammals
Carnivores
Canines
Canis
lupus
Which two animals would be more closely
related, two from the same phylum or two
from the same genus?
Linnaeus’s System
Linnaeus also developed
the modern system of
naming organisms
known as:
Binomial
nomenclature
Why? Common names can vary!
What animal is this?
mountain lion
______________
puma
______________
catamou
______________
cougar
______________
. . . are all names for the same animal
Also, some early scientific names were often
long and difficult to remember…
The European bee, for example, carried the
name Apis pubescens, thorace subgriseo,
abdomine fusco, pedibus posticis glabris
utrinque margine ciliatis.
Binomial nomenclature is a
two-part naming system
that identifies a species
with 2 names:
 Uses Genus & species
 Either Latin or Greek
 Italicized in print
 Capitalize Genus, but
NOT species
 Underline when writing
Turdus migratorius
American Robin
Binomial Nomenclature
Which TWO are more closely related?
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