CLASSIFICATION
is the grouping of
objects or
organisms based
on a set of criteria
How did classification begin?
O Aristotle was the first to create a biological
system of classification over two thousand
years ago.
O Defining characteristics that he used were:
O Animal or plant
O Bloodless or red-blooded
O Habitats
O Size
O Physical Features
A new system was needed!
O Aristotle’s classification
system did not work because
it did not account for
evolution.
A new system emerged in the
1700s
O Carolus Linnaeus
developed the modern
classification system of
TAXONOMY.
O TAXONOMY is a discipline
of biology concerned with
identifying, naming and
classifying species based
on natural relationships.
Classification goes from a
broad set of characteristics
to a specific set of
characteristics
Linnaeus’s
System
O Linnaeus categorized organisms according to
their physical features and behavior.
O Linnaeus named organisms using a system
called BINOMIAL NOMENCLATURE.
O This is a system that gives every species a two
part name.
How to use Binomial
Nomenclature
Homo sapiens
O The first part is the genus (Homo) and the
second part is the species (sapiens)
O The first letter of the genus name is always
capital
O The first letter of the species name is always
lowercase
O If printed it must be italicized, if handwritten
it must be underlined.
Understanding Taxonomy
O Living organisms are
classified according
to 8 main categories
O Domain is the most
general category and
species is the most
specific
How are organism’s classified?
O In order to classify organisms,
scientists use something called a
DICHOTOMOUS KEY.
O The key allow you to examine the
presence or absence of a feature in order
to determine the type of species that you
are looking at.