
Ways to Identify an Unknown ?
 Field Guides
 Dichotomous Keys
 Composed of statements with 2 opposite parts or
categories.
 Choose the statement that is true about an unknown
organism.
Dichotomous Key

Look out for the special check mark to
know which notes to write!
 On a checked slide, write all notes, unless …
 On a checked slide with lots of notes, just write
underlined text!

Classification
System that groups organisms based on common
features that they share

Aristotle
 First man to develop a system to classify organisms
 2 kingdoms

 He subdivided each
kingdom
 Plant- based
division on size
 Herbs
 Shrubs
 Trees
 Animals- based
division on habitat
 Air
 Land
 Sea
Animals: Air Land Sea

Carolus Linnaeus
 Improved classification system
 Based his grouping on physical
features

Linnaeus =Universal name=
Binomial Nomenclature
 All organisms are given a universal name
 Used by all scientists
 Helpful when many common names are used
 Name is composed of 2 names
 Genus name
 Capitalized and comes first!
 Species name
 lower case and comes second
 Both names are underlined
 Example: Tolypeutes matacus – Three Banded Armadillo
Common names are misleading
 Puma
 Cougar
 Mountain Lion
A seahorse is not a
horse, but a fish.
Scientific name
 Myotis macrotarsus
 “Mouse-eared bat with big feet”
 Cat
 Genus name= Felis
 Species name=
 domesticus=house cat
 sylvestris=wildcat
 Human
 Genus name=Homo
 Species=sapien
Kingdom: Animalia (mobile critters; have
many cells; can’t make their own food)
Phylum: Chordata (flexible skeletal rod with
accompanying nerves)
Class: Chondrichthyes (‘fish’ with a
cartilaginous skeleton)
Order: Lamniformes (‘Mackerel’ sharks)
Family: Lamnidae (‘Mackerel’ sharks)
Genus: Carcharodon (from the Greek carcharos
meaning “ragged” or “pointed” and odon
meaning “tooth”)
Species: carcharias (Greek for “shark”)

Modern classification system
 Uses Linnaeus system but adds:
 comparison of body chemistry and development
features
 DNA sequence
 Cytochrome C
 Hemoglobin
 Developmental stages
of embryos
Reclassified

Modern Classification System
 Domain= Eubacteria
 Kingdom=Eubacteria
 Prokaryotic Bacteria
 Domain=Archaea
 Kingdom=Archaebacteria
 Extreamophiles
 Domain Eukarya
 Contains 4 kingdoms




Kingdom=Protista
Kingdom=Fungi
Kingdom=Plant
Kingdom=Animal
Classification
Groups
=Taxa
 A Mnemonic Device:
 Dear
 King
 Philip
 Came
 Over
 For
 Ginger
 Snaps
Each division
contains fewer
organisms, but
shares more features
in common.


Classification Taxa
 Domain is the largest Taxa
 Domain contains one or more
kingdoms
 Domain
 contain the most organisms
 Each kingdom is then
subdivided into:
 Phylum, Class, Order, Family,
Genus, Species
 Species
 contain the fewest organisms but
with the most physical features
in common
Classification
Which two animals are most closely related?