Classification of
Organisms
Mincer/Scully
Why Classify?
• To make it easier to study life!
• Taxonomy- the assigning of a
universally accepted name to a
species.
• Binomial nomenclature- An
organism’s classification is based on
its Genus and species names. The
Genus is ALWAYS capitalized, and the
species name is NEVER capitalized.
– E.g. Homo sapiens (humans), Odocoileus
virginianus (Whitetailed deer)
Linnaeus
• We use a system today that was originally
created by Carl Linnaeus.
• Linnaeus- (1707-1778) A botanist who
created a classification system of
organisms based on their physical
similarities with each other.
• Originally, Linnaeus only had two
Kingdoms, or major categories-Plant and
Animal.
Linnaean System
• King Phillip Came Over For
Grasshopper Soup
• Kingdom
– Phylum
• Class
– Order
» Family
»
Genus
»
Species
Linnaeus vs. Modern
Classification
• Linnaeus
– 2 Kingdoms
– Based on physical
similarities
– Uses only biologists
observations and
knowledge of
organisms
• Modern
– 5 or 6 kingdoms
– Based on physical
similarities AND
genetic similarities
– Uses observations,
knowledge of
organisms,
molecular clocks,
and other genetic
techniques
Modern Classification
• Five Kingdom System: Older system,
lumps all prokaryotic species into one
kingdom: Monera
Animal
Plant
Protist
Fungi
Monera
Six Kingdom Classification
• Keeps Animal, Plant, Fungi and
Protista, and splits Monera into two
Kingdoms:
– Eubacteria-normal everyday prokaryotes
found on Earth
– Archeabacteria- prokaryotes that are
only found in extreme environmental
conditions, like in a salty lake, or in
extreme temperatures; also called
extremophiles.
Three Domains: Six Kingdoms
• Eukarya
–
–
–
–
Animal
Plant
Fungi
Protista
All have
organisms
made of
eukaryotic
cells
• Bacteria
– Eubacteria
• Peptidoglycan
in the cell
walls
Prokaryotic
single celled
organisms
• Archea
– Archeabacteria
• No
peptidoglycan
in the cell walls
Prokaryotic
single celled
organisms that
live in extreme
environments
An Example of Classification
• The Leopard: Panthera pardus
Fungi
• All members are heterotrophic (they
have to eat other organisms for their
food)
• Most are multicellular, and secrete
digestive enzymes into their food
source, then absorb the smaller food
molecules
• Mushrooms are most common
Protista
• “Junk” drawer Kingdom
• Mostly unicellular eukaryotic organisms,
but some multicellular, like kelp.
• VERY diverse array of organisms, from
diatoms to algae.
• Some are autotrophs (make own food)
and some are heterotrophs.
Dichotomous Keys
• In the field, biologists use dichotomous
keys to identify organisms.
• Dichotomous key-A chart that identifies
organisms based on their characteristics.
Its used by excluding organisms based
on their OBSERVABLE features.