Unit 11:
Classification of
Living Things
Finding Order in
Diversity
Tacitus bellus
Populus tremuloides
Quaking Aspen
• To study the diversity of life, biologists
use a classification system to name
organisms and group them in a logical
manner.
• Taxonomy is the branch of biology
that groups and names organisms
based on studies of their different
characteristics.
• Biologists who study taxonomy are
called taxonomists.
• Classification systems change with
expanding knowledge.
Carolus Linnaeus
• Swedish botanist
• Developed Binomial Nomenclature
• Two-word naming system
– Genus
Carolus von
Linnaeus
(1707-1778)
» Noun, Capitalized,
Underlined or Italicized
– Species
» Descriptive, Lower Case,
Underlined or Italicized
– Each species is assigned a two-part
scientific name
» Ex. Ursus arctos
System of
Classification
• Linnaeus’s hierarchical system of
classification includes eight levels (from
largest to smallest)
• Grizzly Bear (common name)
Ursus arctos
(scientific name)
–
–
–
–
–
–
–
–
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Eukarya
Animalia
Chordata
Mammalia
Carnivora
Ursidae
Ursus
arctos
Each of
the levels
is called a
TAXON
D
K
P
C
O
F
G
System of
Classification
• Taxonomic categories, an
acronym:
– Domain
– Kingdom
– Phylum
– Class
– Order
– Family
– Genus
– Species
Dear
King
Phillip
Came
Over
For
Good
Soup
Evolutionary
Classification
• Phylogeny – evolutionary
relationships among organisms
• Evolutionary classification –
strategy of grouping organisms
together based on their
evolutionary history
– Fossil record
– Comparative homologies
– Comparative sequencing of
DNA/RNA among organisms
– Molecular clocks
Taxonomic
Diagrams
Phylogenetic Tree: Represent
hypothesized evolutionary
relationships
Mammals
Looks like a
Branch on a
tree
Turtles
Lizards and Snakes
Crocodiles
Birds
Taxonomic
Diagrams
Cladogram
Mammals
Turtles
Lizards and Snakes
Crocodiles
Birds
Which
organism is
the
outgroup
Mammals
Which 2
organism
are more
closely
related
Crocodiles
and birds
Attempt to trace the
process of evolution by
focusing on shared features
Dichotomous Keys
Identify Organisms
• Dichotomous keys contain pairs of
contrasting descriptions.
• After each description, the key directs
the user to another pair of descriptions
or identifies the organism.
Example:
1. a) Is the leaf simple? Go to 2
b) Is the leaf compound? Go to 3
2. a) Are margins of the leaf jagged? Go to 4
b) Are margins of the leaf smooth? Go to 5
Classification of Living Things
Domains
(Notice the domains on the
chart)
• Most inclusive category
• Larger than a kingdom
• There are 3
– Eukarya – includes the kingdoms
» Protists, Fungi, Plants & Animals
– Bacteria – corresponds to the
kingdom Eubacteria
– Archaea – corresponds to the
kingdom Archaebacteria
Slides 17-23
• Is more specific with the
classification
Kingdoms
• (Eubacteria and Archaebacteria)
Prokaryotes, with or without peptidoglycan
in cell walls
• Protista – Eukaryotes, diverse, not fungi,
plants, or animals
• Fungi – Eukaryotes, multicellular (except
yeasts), heterotrophic, chitin in cell walls
• Plantae – Eukaryotes, multicellular,
autotrophic, cell wall containing cellulose
• Animalia – Eukaryotes, multicellular,
heterotrophic, no cell wall
Kingdom Eubacteria
Streptococcus mutans
(can cause endocarditis
and dental caries)
Bacillus anthracis
(spores can live in soil
for years)
•
•
•
•
•
Common name: Bacteria
Unicellular prokaryotes
Peptidogylcan in cell wall
Ecologically diverse
Basic shapes are cocci, bacilli,
spirilla
• Reproduce both sexually and
asexually
Kingdom Archaebacteria
Archaea
first detected in
extreme
environments, such
as volcanic hot
springs.
• Cell wall does not contain
peptidogylcan
• Cell membrane contains unusual lipids
not found in other organisms
• Live in extreme environments (devoid
of oxygen):
– volcanic hot springs
– brine pools
– black organic mud
Kingdom Protista
• A classification problem – consists of
organisms that cannot be classified
as animals, plants, or fungi
• Most unicellular, some colonial and
some multicellular
• Autotrophic and heterotrophic
• Some move with flagella, pseudopods
or cilia
• Animal-like, plant-like and fungus-like
groups
• Reproduce by mitosis and meiosis
Entamoeba histolytica
Kingdom Fungi
Boletus zelleri
(Edible, but often
infected with fly
larvae)
Epidermophyton
floccosum
(one of the causes of
athlete's foot)
• Most feed on dead, decaying
organic matter by secreting
digestive enzymes into their food
source then absorbing it into their
bodies
• Cell walls of chitin
• Most multicellular; some
unicellular
• Heterotrophic
Kingdom Plantae
Sunflowers in
Fargo, North Dakota
Ginkgo biloba
Ginkgos are often very
long-lived. Some
specimens are thought
to be more than 3,500
years old.
• Multicellular
• Nonmotile – cannot move
from place to place
• Cell wall with cellulose
• Mostly photosynthetic
autotrophs
Kingdom Animalia
Hymenoptera
Dialictus zephrum
Txodes scapularis
Deer tick
•
•
•
•
Multicellular
Heterotrophic
No cell walls or chloroplasts
Incredible diversity
Hierarchical System
of Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
• From
general
to
more
specific
Species
How Many Kingdoms?
6
Kingdoms
• Activity: What am I?