Download The Classification of Living Organisms

Copyright 2010. PEER.tamu.edu
Why classify things?
 Say you go to the mall to get some new clothes.
 Where would you go?
 How do you know to go to that particular store?
How is a mall organized?
 Food Court
 Big Department Stores
 Specialty Clothing Stores
 Jewelry Stores
 Electronics Stores
 Shoe Stores
 Toy Stores
 Kiosks
 Can you imagine if the mall was just one big store and
you had to go through rows and rows of “stuff” to find
the right clothes in the right brand and the right size
for you?
 How long would that take?
Big Idea:
 The mall, your city, your school
and your closet (hopefully) are
all organized so that you and
other people can get things
done without wasting extra
time and effort.
 Scientists also organize or
classify things so that they are
easier to investigate and
understand.
Here are some things that
scientists classify or organize:
 The elements
 The human body
 Interactions in
Ecosystems
Scientists also Classify Living
Organisms
 How could you classify these living things?
Quick, organize these living things
into groups:
Did you do it like this?
Or this?
Are there any other ways to group
these living things?
Classification of Living Things
TaxonomyThe science of dividing and arranging things into
a classification system.
Early man probably classified many things. What
do you think he classified????????????????????
Early Classification Systems for
Living Things
 Plant Kingdom
 Grasses
 Herbs
 Trees
 Animal Kingdom
 Fish
 Creeping creatures
 Fowl
 Beasts
 Cattle
Aristotle
 400 BC
 Attempted a classification
system for over 500 species of
animals
 Categorized animals as air
dwellers, land dwellers, and
water dwellers
 Classified the dolphin as a land
dweller
 Keen observer of nature
Pliny
 23 – 79 AD
 Scholar during the time of the
Roman Empire
 Wrote 37 volume Natural
History
 Unicorns, mermaids, flying
horses
 Excellent attempt to classify all
known information
Middle Ages (AD 500 – 1400)
 Fantastic creatures
rumored to exist
 Big Foot, Loch Ness
Monster, Abominable
Snowman
 Always inhabit far off
regions
 “Dragon teeth”
European explorers returned home with many new types of
organisms
Discovery of microscope led to discovery of
microorganisms
Galileo invented telescope
Anton van Leeuwenhoek 1632 -1723
 Had his own drapery business



Leeuwenhoek’ s
early microscope

where he used lenses to examine
cloth for quality.
Improved upon the quality of
these lenses until they were able
to magnify up to about 300X.
The tiny living creatures that he
observed in many places – soil,
water, souring milk – were called
“animalcules” – little animals.
Also saw these creatures on the
plaque taken from his own teeth.
The microscopic world was now
being observed. Is two Kingdoms
enough to classify everything?
Carolus Linnaeus
 Founder of Modern
Taxonomy
 1737 – published system
of taxonomy entitled
Systema Naturae
 Instituted binomial
nomenclature
 Arranged related genera
into orders; orders into
classes
Binominal Nomenclature
 Two Word Naming System
 Genus, Species
 Genus ALWAYS capitalized first letter
 Species lower case
 Example: Homo sapien
or
Homo sapien
The most basic classification system is based on Domains
and Kingdoms. Organisms are classified into Domains or
Kingdoms based on these characteristics:
 1. Whether they are unicellular or multicellular.
 2. Whether they are prokaryotic or eukaryotic.
 3. Whether they have a cell wall or cell membrane.
 4. Whether they have membrane bound organelles.
 5. Whether they are autotrophic or heterotrophic.
 6. Whether they reproduce sexually or asexually.
 7. How they tolerate heat, salt or other extreme
conditions.
Old Classsification System
Kingdom
Phylum
Class
Order
Family
Genus
Species
New Classification System
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
What information about an organism do
taxonomists use when they classify?
 Structural Information
skeletal structure or leaf anatomy
 Biochemical Information
DNA, RNA, protiens
 Cytological Information
prokaryotic/eukaryotic, chromosome number
 Embryological Information
appearance of organisms in early stages of development
 Behavioral Information
Some species of crickets can only be distinguished on the
bases of their mating calls.
Comparative Embryology of Vertebrates
Horizontal Cladogram
Vertical Cladogram Ancestor at
Bottom
Basic Classification
Domains:
Archaea
 There are three Domains
of living organisms based
on their characteristics:
 Archaea (also called
Archaebacteria)
Eubacteria
Eukaryota
 Eubacteria (also
called Bacteria)
 Eukaryota (also
called Eukarya)
Life’s diversity, which was originally divided into five kingdoms, has
been expanded to six when Kingdom Monera was divided into two.
http://lesliehorne.tripod.com/sitebuildercontent/sitebuilderpictures/sixkingdoms01.gi
New methods of comparison such as DNA sequences have led to an
ongoing reevaluation of the number & kinds of kingdoms ranging from
six to twelve. Most taxonomists now group kingdoms into a higher
classification category called a domain.
Basic Classification
Kingdoms:
 The Domains can also be split into Kingdoms which
further divide the organisms by their characteristics.
Domain Archaea
“Archaea” means “ancient” bacteria.
Organisms in Archaea are:
 Unicellular
 Prokaryotic
 Autotrophic or Heterotrophic
 Reproduce asexually
Aerial view of hot spring at Yellowstone
 Bacteria that have adapted to extreme environments.
 Some can survive in extremely hot environments like around
hot springs and geysers. They are called thermophiles.
 Some can survive in extremely salty environments like The
Great Salt Lake in Utah. They are called halophiles.
 The Domain Archaea has one Kingdom, also called
Archaea
This hot spring is flowing into the Firehole River in Yellowstone.
The colors are caused by different varieties of archaebacteria and
other microscopic life forms. Scientists can distinguish
temperatures of water by the colors present.
Domain Eubacteria






“Eu” means “true” bacteria
Unicellular
Prokaryotic
Autotrophic or Heterotrophic
Reproduce Asexually
Most abundant organisms on earth.
One bacterium can give rise to 10
million in 24 hours.
 They are found in almost every
habitat on earth.
 The Domain Eubacteria has one
Kingdom, also called Eubacteria.
 Many are common infectious
agents.
This is a picture of bacteria on the skin. Bacteria can be shaped like a sphere
(cocci) like this picture, like a rod, or like a spiral. The structure in the middle of
this picture is a hair follicle with a hair growing out of it.
Terminology:
 The Domains Archaea and Eubacteria are commonly
grouped together in discussion and called
prokaryotes because they lack membrane bound
nuclei and membrane bound organelles.
Nucleus
and
Organelles
Domain Eukaryota (Eukarya)
 Eukaryotic
 Very Diverse
 Unicellular or Multicellular
 Autotrophic or Heterotrophic
 Reproduces Sexually or Asexually
 Can be split into 4 Kingdoms Protista
 Fungi
 Plantae
 Animalia
The 4 Kingdoms in Eukaryota
Protista
Plantae
Mostly Unicellular and Microscopic
Autotrophic or Heterotrophic. Can be
infectious agents
Examples:
Amoeba
Algae
Daphnia
Plasmodium
(causes malaria)
Multicellular Green Plants
Autotrophic through Photosynthesis
Have a Cell Wall
Examples:
Mosses
Ferns
Trees
Flowering Plants
Fungi
Animalia
Multicellular
Heterotrophic
Decomposers
Can be infectious
agents
Examples:
Mushrooms
Athlete’s foot
Bread Mold
Multicellular Animals
No Cell Wall
Heterotrophic
Examples:
Insects
Spiders
Crabs
Humans
Birds
D
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K
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D
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Think Break:
 Where do Viruses fit in this classification system?
 Example: AIDS, Common Cold, Flu, Herpes, and
Small Pox
How would you classify these?
 A organism that can exist in extremely hot
temperatures. It is made of only one cell with no
nucleus.
 Domain: Archaea
Kingdom: Archaea
 A green organism growing from the ground. It is
multicellular and undergoes photosynthesis. It’s cells
have nuclei and cell walls.
 Domain: Eukaryota
Kingdom: Plantae
Try two more:
 This organism is microscopic and one-celled. It lives
in colonies where millions of others like it are present.
It does not have a nucleus. It cannot survive in
extreme conditions. Could be an infectious agent.
 Domain: Eubacteria
Kingdom: Eubacteria
 This organism is multicellular. It is a decomposer. Its
cells have nuclei.
 Domain: Eukaryota
Kingdom: Fungi
Classification Systems Can Change!
Can you guess why?
 Classification systems
change as new organisms
are discovered and as more
information is gained about
living organisms.
 Science is a “work in
progress” and things change
as new evidence is found.
Even though classification is not an
exact science, it is a part of almost every
aspect of our lives.
Which one would you choose? Why?
Classification of Bacteria
•Kingdom Monera has been replaced with two
kingdoms.
•Kingdom Archaebacteria – primitive bacteria that
live in the harsh environments that resemble the
conditions of the early earth when life was first
evolving.
•Kingdom Eubacteria – larger kingdom -- includes
heterotrophic & autotrophic organisms; some of
the autotrophs are photosynthetic; others are
chemosynthetic. Harmful & beneficial forms.
•Separated because of biochemical differences.