Classification of
Living Things
Chapter 18
I. Why are things grouped???
A.) To “classify” something means you
are…
- Identifying and naming organisms
- Grouping organisms in a logical
manner
Biologists have identified and
named over______________
species so far.
Estimates = between 2-100 million
species yet be discovered
1.5 million
What is the Purpose of Grouping
Things?
1. Need for order &
organization
2)
Logical means for
naming organisms.
3)
Ease of communication
with other scientists.
4)
When new organisms
are discovered,
_______________ =
branch of biology that
names and groups organisms
Naming and organizing animals
into groups with biological
significance helps make sense
of relationships.
BIRDS . . . ?
Image from: http://www.flagsplus.com/flags/21778_bird_collage.jpg
A good classification system:
places organisms in a group with
other organisms that are
A good classification system:
Uses names that are _________
Can _____ as new data is discovered
Shows _____________ of organisms
UNIQUE
CHANGE
II. METHODS OF
CLASSIFICATION
A.) Early System
Aristotle’s system
ANIMALS:
Based on
structure
PLANTS:
Based on
PROBLEMS WITH THIS
SYSTEM?
Categories were too broad
1.
Example:
“Air Dwellers’
PROBLEMS WITH THIS
SYSTEM?
Common names can vary
2.
Example:
puma,
catamount,
mountain lion,
cougar
3. Language can vary
Chipmunk
Streifenhornchen(German)
Tamia (Italian)
Ardilla listada (Spanish)
4. Common names can be misleading
Sea cucumber
sounds like a plant
but… it’s an animal!
Ex:
A jellyFISH isn’t a fish,
but a seaHORSE is!
Image from: http://en.wikipedia.org/wiki/Jellyfish
Common names can be misleading
In the United States,
BUZZARD refers to a
vulture.
In the United Kingdom,
BUZZARD refers to a hawk
http://www.camacdonald.com/birding/HoodedVulture(HM).jpg
By mid 19
th
century,
scientists recognized that
using common names was
confusing.
Scientists agreed to use
____________ to give
a single scientific name
to each species.
EXAMPLE: RED OAK
Quercus foliis obtuse-sinuatis
setaceo-mucronatis
Names too hard and long to remember!
“oak with deeply divided leaves with
deep blunt lobes bearing hair-like
bristles”
Different scientists described different
characteristics.
Carolus Linnaeus comes to
the rescue!
Swedish botanist who
created a new
classification system
This system is still used
today!
(1707-1778)
Linnaeus’ System was based
on…
the physical &
structural
similarities
between
organisms.
classifying
organisms by
assigning them a 2-
part name:
Therefore it showed…
the
Linnaeus’s System…
A hierarchy of levels, from most
general to most specific
8 different taxonomic levels
(called TAXONS)
D
omain
Human
Earth K
ingdom
animalia
Hemisphere P
hylum
chordata
BINOMIAL NOMENCLATURE
(
2-part name
, naming system): A.K.A. an
organism’s
scientific identity
1
st
name = _______________
Always capitalized
2
nd
name = _________________
–
Always lower case
Both names are ______________ or
written in ____________.
GENUS NAME
SPECIES NAME
GENUS = group of closely related
species
GENUS =
Ursus
(Includes many kinds of bears)
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
Ursus
Binomial nomenclature
Humans
Homo sapiens
Homo sapiens
MODERN EVOLUTIONARY
CLASSIFICATION
In a way, organisms determine
who belongs to their species
by choosing with whom they
will __
______
__!
Only organisms within the same
species
can mate and produce
fertile offspring
A. What gets classified?
Only living things are classified, not
VIRUSES
*** Viruses cannot reproduce on their own
B. What Language?
Taxonomists are required to use the
language of Latin
Why?
A.)
It is no longer used so it is an
unchanging language
B.)
Many modern words are taken from
Latin
C.)
Latin was understood by scientist at
the time taxonomy was first developed
C. Species are classified
according to…
1.
Structural similarities.
2.
Cellular organization
Prokaryote vs.
3. Biochemical
Similarities
Protein
DNA
FUN FACT:
Similarities in DNA can be used to
help show evolutionary relationships
and how species have changed.
Images from: Biology by Miller and Levine; Prentice Hall Publishing©2006
African vulture American vulture Stork
“FUNNER” FACT:
American vultures have a peculiar
behavior. When they get overheated,
they urinate on their legs to cool off
Images from: Biology by Miller and Levine; Prentice Hall Publishing©2006
African vulture American vulture Stork
4. Genetic Similarities
D. Tools for Taxonomists
1.
Dichotomous Keys
An organized set of couplets of
mutually exclusive characteristics of
biological organism.
It’s a type of taxonomy tool that gives
Dichotomous
Keys
What it does…
A.)
Compares
the
characteristics
of an
unknown
b). Go from…
general to
specific characteristics
C.) If the
organism falls into
one category, you
go to the next
indicated couplet
until correctly
identified
2.) Phylogenetic
Classification Models
a) The evolutionary history of a species
is called
phylogeny (fa-la-jen-ee
*The study of the evolutionary
relationships among organisms.
Relating to or based on evolutionary
Cladistics
B.) Cladistics is…
a system that groups organisms by
common ancestry.
C.)
A graphic representation of an
organism’s ancestors is called a a
Derived characters
appear at branches
of the cladogram
showing where they
first arose.
Cladograms help
scientists understand
how one lineage
Domain Bacteria Archaea Eukarya Kingdom Eubacteria
Archaea-bacteria
Protista Fungi Plantae Animalia
Cell type Prokaryote Prokaryote Eukaryote Eukaryote Eukaryote Eukaryote
Cell
structures Cell was w/peptidoglycan Cell was w/peptidoglycan Cell walls of cellulose, some
w/chloroplasts
Cells walls of chintin (N2 containing polysacchorides) Cell walls of cellulose, chloroplasts No cell walls or chloroplasts Number of cells
Unicellular Unicellular Mostly
unicellular Some colonial Some multicellular Most multicellular Some unicellular
Multicelluar Multicelluar
Mode of nutrition Autotroph or hetertrop Autotroph or hetertrop Autotroph or hetertrop
Hetertrop Autotroph Hetertrop
Examples E. coli
Methanogens
-
microorganisms that
produce methane as a
metabolic by-product in
anoxic conditions
-they are common in
wetlands,
-they are responsible for
marsh gas
-in the guts of animals such
as cows and humans, they are
responsible for the methane
content of belching and
Halophiles
-organisms that thrive in
environments with very high
concentrations of salt
- found anywhere with a
concentration of salt five times
greater than the salt
