Classification of Living Things
Classification of Living Things
 Taxonomy: Branch of biology that names organisms
according to their characteristics.
 Putting things into orderly groups based on similar
characteristics.
 Why do scientists classify?
Biologists classify living organisms to answer questions
such as:
- How many known species are there?
- What are the defining characteristics of each species?
- What are the relationships between these species?
Aristotle
 Aristotle
 Greek philosopher and
teacher more than
2000 years ago
 The first person to
group or classify
organisms
(300 B.C.)
Aristotle
PLANTS:
Based on
size of stem
ANIMALS:
Based on
where they lived
Limitations of Early Classification
1. Not all organisms fit into Aristotle’s
2 groups (plants or animals)
Ex: Bacteria
Fungi
Images from: http://www.leighday.co.uk/upload/public/docImages/6/Listeria%20bacteria.jpg
http://danny.oz.au/travel/iceland/p/3571-fungi.jpg
Limitations of Early Classification
2. Common names can be misleading
Ex:
A jelly fish isn’t a fish,
but a seahorse is!
Sea cucumber
sounds like a plant
but… it’s an animal!
Image from: http://www.alaska.net/~scubaguy/images/seacucumber.jpg
Limitations of Early Classification
3. Common names vary from
place to place
Ex: puma,
catamount,
mountain lion,
cougar
are all names
for same animal
Image from: http://www4.d25.k12.id.us/ihil/images/Cougar.jpg
Limitations of Early Classification
4. Same organisms
have different
names in different
countries.
Chipmunk
Streifenhornchen (German)
Tamia (Italian)
Ardilla listada (Spanish)
Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm
Limitations of Early Classification
Early Solution:
Description of
Organism Using
Latin Names
RED OAK
Quercus foliis obtuse-sinuatis setaceo-mucronatis
“oak with leaves with deep blunt lobes bearing hairlike bristles”
Limitations of Early Classification
 Problem with Latin Name descriptions?
- Names too long and difficult to remember
- Names don’t illustrate evolutionary
relationships
Carolus Linneaus
Devised a new
classification
system based on
morphology
(Organism’s form
and structure)
(1707-1778)
“Father” of taxonomy and binomial nomenclature
Carolus Linnaeus
 Linnaeus’s Classification System
 Organisms grouped in a hierarchy of
seven different levels
 Each organism has a two part
scientific name
Binomial Nomenclature
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kids
Prefer
Cheese
Over
Fried
Green
Spinach
Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Carnivora
Family Felidae
Genus Panthera
Species leo
http://www.vetmed.wisc.edu/dms/fapm/personnel/tom_b/2004-lion.jpg
Binomial Nomenclature
 Binomial Nomenclature: Two name
naming system
 Italicized or Underlined
 1st Name = Genus
 Capitalized
 2nd Name = Species Identifier
 Lower case
Binomial Nomenclature
Vampire bat
Desmodus rotundus
Image from: http://212.84.179.117/i/Vampire%20Bat.jpg
Eastern chipmunk
Tamias striatus
Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm
Binomial Nomenclature
Humans
Homo sapiens
Homo sapiens
Image from: http://www.earlylearning.ubc.ca/images/photo_baby.jpg
Modern Taxonomy
 Modern taxonomy involves the use of Linnaeus’s
naming/classification system, but with additional
kingdoms.
Modern Taxonomy
Organizes
living things
in the
context of
evolution
Modern Taxonomy
 Scientists use a variety of information in
order to classify organisms:
1. Fossil Record
2. Morphology
3. Embryology
4. Chromosomes
5. Macromolecules (DNA and Proteins)
1. FOSSIL RECORD
We can trace some
changes over time
through the fossil
record.
Evolutionary history =
PHYLOGENY
2. MORPHOLOGY
Shape and Function
Image from:
http://www.angelfire.com/ab7/evolution12/evolutionclues.html
Morphology
 Homologous Characteristics:
 Same embryological origin (may have
similar structure and function)
 Example: Bat Wing and Human Arm
Homologous characteristics suggest a
recent common ancestor
Morphology
Bat wing
and human arm
develop from
same embryonic
structures
HOMOLOGOUS
STRUCTURES
Morphology
 Analogous Characteristics:
 May have similar structure and function, but
different embryological origin
 Example: Bird Wing and Butterfly Wing
Analogous characteristics evolved separately.
Organisms not necessarily closely related.
ANALOGOUS
STRUCTURES
Bird wing and
butterfly wing
have evolved with
similar function
BUT
different structure
inside.
http://uk.dk.com/static/cs/uk/11/clipart/bird/image_bird003.html
Insects and birds
NOT closely related!
http://www.naturenorth.com/butterfly/images/05a%20tiger%20wing.jpg
I don’t get it!
 Analogous characters  the same function
but different underlying construction.
 Homologous characters  different functions, but
show an anatomical similarity inherited from a
common ancestor. **Important for cladograms!**
3. Embryology
Animals whose embryos develop
in a similar pattern may be related
Image from: http://calspace.ucsd.edu/virtualmuseum/litu/03_3.shtml
Even differences show relatedness
amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds,
reptiles, and mammals, which lines the chorion and contains the fetus and the
amniotic fluid
http://www.southtexascollege.edu/nilsson/4_gb_lecturenotes_f/4_gb_24_cla_ani_ve_spr2003.html
4. Chromosomes
Similar karyotypes suggest closer relationships.
Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png
Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
Human- 46 chromosomes
Chimpanzee- 48 chromosomes
Even differences show relatedness
Chimpanzees have 2 smaller chromosome pairs we don’t have
Humans have 1 larger chromosome pair (#2) they don’t have.
Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png
Chimpanzee: Middle School Life Science , published by Kendall/Hunt.
5. Macromolecules
Comparison of macromolecules
such as Proteins and DNA
Organisms with similar
sequences are (thought to be)
more closely related.
Macromolecules
Evolutionary Relationships
 Determined through the use of:
1.
2.
3.
4.
5.
Morphology
Fossil Record
Embryology
Chromosomes
Macromolecules
Evolutionary relationships can be illustrated on a
phylogenetic tree
Cladistics
 Shows evolutionary relationships based on
“shared derived characteristics”
 Cladistic relationships illustrated through the use
of a Cladogram
Phylogeny:
Evolutionary History
Cladogram
 The greater the
number of derived
characters shared
by groups, the
more recently the
groups share a
common ancestor.
Domains
 Domains are taxonomic groups that are even bigger than
kingdoms. Each of the six kingdoms belongs to a single
domain.
 Three Domains:
 1. Archaea
 2. Bacteria
 3. Eukarya
Do
Kids
Prefer
Cheese
Over
Fried
Green
Spinach?
Domain Bacteria
 Eubacteria are
prokaryotes whose cell
walls contain
peptidoglycan.
 “True bacteria”
Domain Archaea
 Archaea are thought to be more ancient than
bacteria and yet more closely related to our
eukaryote ancestors.
 Cell walls without
peptidoglycan
 They are called extremophiles because
they can live in extreme environments.
Domain Eukarya
 All eukaryotes are classified in Domain
Eukarya.
 Domain Eukarya contains Kingdom
Protista, Kingdom Fungi, Kingdom Plantae,
and Kingdom Animalia.
Kingdom Archaebacteria
 Some archaebacteria are heterotrophs, but some are
autotrophs.
 Most archaebacteria are unable to move, but a few
can move.
 Archaebacteria are the old known life forms.
 Why are archaebacteria not classified with “modern
bacteria”?
 Archaebacteria and eubacteria are chemically different!
Kingdom Archaebacteria
 Cool archaebacteria info:
 Three divisions of archaebacteria:
Methanogens: methane producing organisms
Thermophiles: These can live in extremely hot, acidic environments
like sulfur springs.
Halophiles: Can only live in bodies of concentrated salt water, like
the Dead Sea.
Kingdom Eubacteria





Traditional prokaryotic bacteria
Unicellular.
Some are autotrophic, some are heterotrophic.
Found in soil, water, human body, etc.
Esterichia coli (E. coli) is found in large numbers in human
intestines, where it produces vitamin K.
Kingdom Eubacteria
 Unlike archaebacteria, eubacteria require oxygen.
 Some bacteria contain cilia or flagella which allows them to
move.
Kingdom Protista
 Eukaryotic organisms.
 This is why they are not considered bacteria!
 Most protists are single-celled but some are simple,
multicellular organisms
 “Junk Drawer Kingdom” or “Odds and Ends Kingdom”
 Some protists are autotrophic, some protists are
heterotrophic.
 Animal-like protists, plant-like protists
Kingdom Protista
Most protists are able
to move, but some
cannot
Kingdom Fungi
 Molds and mushrooms are examples of fungi.
 Fungal cell walls contain chitin.
 (cell walls of plants contain cellulose).
 The study of fungi is known as mycology.
 Fungi are more closely related to animals than to
plants!
 Usually, the only fungi that we see are reproductive
structures. Tasty!!
Kingdom Plantae
 Plants are eukaryotic, multicellular organisms.
 They are autotrophs- they make their food through
photosynthesis.
 Plants can be found on land and in shallow water
(where there is light)
Kingdom Plantae
 Plant cells have cell walls
 Made up of cellulose, to provide them with a rigid
structure
 Some plants reproduce through both asexual and
sexual reproduction.
Kingdom Animalia
 This kingdom contains many complex, multicellular
organisms.
 All animals are heterotrophic.
 All animals are able to move, even if it is only during
some stages of the life cycle.
Kingdom animalia
 All animals are eukaryotic organisms, but animal cells
do not have a cell wall.
 Most animals reproduce through sexual
reproduction, but some are able to reproduce
asexually (or both!).
 The most simple organism
in the kingdom animalia
is a sponge.
 A dichotomous key is a classification key
that gives the students two choices to
choose from before moving on to the next
set of choices.
Dichotomous Key activity
 With the person at your table, create a dichotomous
key for the shoes at the front of the room.
Remember, this should be a series of two choices that
each lead you to next series or to the correct shoe.
You can use descriptions in your choices, such as,
casual or dress shoe.
1 a. Men’s ----------go to 2
1b. Women’s ------go to 3
2 a. Casual ----------Converse
2 b. Dress ------------ Merrell
3 a. Casual -----------go to 4
3 b. Dress ------------go to 7
4 a. Open toe -------go to 5
4 b. Closed toe -----go to 6
5 a. Brown ------------Route 66 flip-flop
5 b. Black --------------Yellowbox flip-flop
6 a. Brown ------------Merrell
6 b. Blue ----------------Reef
7 a. Open toe---------go to 8
7 b. Closed toe-------go to 9
8 a. Purple ------------Mossimo
8 b. Silver -------------Kelly & Katie
9 a. Pointy toe ------ DL
9 b. Round toe------Madden Girl
What type of morphological
characteristic are these an
example of?
Homologous
If the Bobcat and Lion are in the
same Order, they are also in the
Class, Phylum, & Kingdom
same _______________.
What type of morphological
characteristic are these an
example of?
Homologous
 Which two are
analogous?
 Which two or
homologous?
What type of morphological
characteristic are these an
example of?
Analogous
Fill in the cladogram with the following organisms:
Pigeon, Hagfish, Chimpanzee, Lizard, Perch, Mouse,
Salamander
Fill in the concept map with the
missing kingdoms.
Write the Western Diamondback Rattlesnake’s
scientific name in the correct format for
binomial nomenclature.
crotalus atrox
Crotalus atrox