The Classification System

 Organisms are classified in
order to easily identify
them, show differences
and be able to work with
them.
 Carl Linneaus developed
the system we use now. It
has been modified some as
we discover new
organisms, both living and
extinct.
The Classification System

Domain is the category that
is the most general. Then
comes kingdom (there are
6). Next is phylum, then
class followed by order,
family, genus and finally
species which is the most
specific.
Dear King Phillip Came
Over For Good Soup
Binomial Nomenclature

All organisms are given a name that
has 2 parts- genus and species.
Example- humans= Homo sapiens
The name is descriptive of the
organism or in honor of the
“discovery.”
Dichotomous Key

 Once organisms are classified, it is possible to
identify their relationship to a new organism or to
identify an unknown organism.
 A dichotomous key provides 2 choices each time to
eventually end with the identity of the organism.
How are organisms classified?

There are several criteria to consider
when grouping organisms together or
keeping them in separate groups.
1. Physical similarities- example: all
birds have bones, wings and feathers; no
other organisms has the combination of
all 3.
How are organisms classified?

2. Evolutionary history- How closely related are
they to each other? Even though a shark and dolphin
share many physical features, they are far apart on
the basis of a common ancestor.
3. Biochemical similarities- shared DNA sequences
4. Similarities in reproduction and diet- this can be
used to group organisms that look very different
(American vultures and storks), or to separate some
that seem very similar (hamsters and guinea pigs.)
Organization of Organisms

 All organisms will fit into one of 3 domains:
 Eukarya- contains the kingdoms Protista, Fungi,
Plantae and Animalia
 Bacteria- contains the kingdom Eubacteria
 Archaea- contains the kingdom Archaebacteria