CLASSIFICATION:
Organizing Life’s Diversity
HOW CLASSIFICATION BEGAN
 Organizing
items can help you
understand them better & find them more
easily.
 Biologists organize living things into
groups


Classification = the grouping of objects or
information based on similarities
Taxonomy = the branch of biology that
classifies organisms.
WHY CLASSIFY?
Three reasons:
 It helps to identify relationships between
organisms
 It requires scientists to identify important
characteristics of organisms
 It helps to avoid confusion


An organism may have misleading or multiple
common names (ex. Seahorse or mountain
lion/cougar/ panther/ puma)
Only one scientific name (Puma concolor)
ARISTOTLE
 Greek
philosopher who developed
the first biological classification
system
 Classified things as plants or
animals



He didn’t know anything about
microscopic organisms like bacteria
Plants were grouped as herbs, shrubs,
or trees
Animals were grouped by where they
lived or spent most of their time land, air, or water
LINNAEUS
 Swedish
botanist who developed our current
classification system
 Based on physical and structural similarities
 Groupings revealed relationships between
organisms

Scientists proposed that structural similarities
reflect evolutionary relationships
DOUBLE-NAME SYSTEM
 Binomial
nomenclature = twoword naming system developed by
Linnaeus





1st word = Genus
2nd word = species
Like a first & last name
Humans are Homo sapiens.
House cats are Felis catus
 Names

are Latin
It is no longer used in conversation so
it doesn’t change
BIOLOGICAL CLASSIFICATION

Scientists try to identify relationships as a basis for
classification
Compare internal & external structures, geographical
distribution, and genetics
 Makes it easier to understand biological diversity
 Dichotomous keys are used to identify the
characteristics by which organisms are classified.


Benefits of taxonomy:
Offers a framework to study evolutionary relationships
 Useful for identifying dangerous organisms (poison oak,
holly berries, etc)
 Economy – discovery of new resources for lumber,
medicines, and energy

HOW LIVING THINGS ARE CLASSIFIED
 Taxa/taxon
= a group of organisms
 Seven Taxa categorize organisms from most
general to specific characteristics.
1.
2.
3.
4.
5.
6.
7.
Kingdom =group of phyla
Phylum (in plants - division) = a group of classes
Class = group of related orders
Order = group of related families
Family = group of genera that share
characteristics
Genus (genera) = group of closely related species
Species = Latin name for an individual organism
EXAMPLE

lions, tigers, and leopards
Kingdom: Animalia
 Phylum: Chordata
 Class: Mammalia
 Order: Carnivora
 Family: Felidae
 Genus: Panthera
 Each are a different species

SIX KINGDOMS OF LIVING THINGS
o
Kingdom Eubacteria

o
Kingdom Archaebacteria

o
decomposers
Kingdom Plantae

o
Diverse catch-all group
Kingdom Fungi

o
Chemosynthetic Bacteria
Kingdom Protista

o
Bacteria
plants
Kingdom Animalia

animals