CLASSIFICATION
• Biologists want to better understand organisms so
they organize them.
• One tool that they use to do this is classification—the
grouping of objects or information based on
similarities.
How classification began…
• Taxonomy is the branch of
biology that groups and
names organisms based on
studies of their different
characteristics.
• Biologists who study
taxonomy are called
taxonomists.
Aristotle’s System
• The Greek philosopher Aristotle (384-322 B.C.)
developed the first widely accepted system of
biological classification.
• He classified all the organisms he knew into two
groups: plants and animals.
Aristotle’s System
• He subdivided plants into three groups, herbs, shrubs,
and trees, depending on the size and structure of a
plant.
• He grouped animals according to various
characteristics, including their habitat and physical
differences.
Aristotle’s System
• According to his system, birds, bats, and flying insects
are classified together even though they have little in
common besides the ability to fly.
• As time passed, more organisms were discovered and
some did not fit easily into Aristotle’s groups, but many
centuries passed before Aristotle’s system was
replaced.
Carolus Linnaeus
(1707-1778), a
Swedish botanist
• Linnaeus’s system was based on physical and
structural similarities of organisms.
He improved the system
of naming plants and
animals by a two-word
name to identify the
genus and species.
“binomial nomenclature”
Linnaeus’ System
• Linnaeus’ showed relationships among
organisms.
• Eventually, some biologists proposed that
structural similarities reflect the evolutionary
relationships of species.
• This way of organizing
organisms is the basis of modern
classification systems.
Species Scientific Names
• Modern classification systems use a two-word
naming system called binomial nomenclature
that Linnaeus developed to identify species.
• In this system, the first word identifies the
genus of the organism.
• A genus (JEE nus) (plural, genera) consists of
a group of similar species.
• The second word, which sometimes describes a
characteristic of the organism, is called the
specific epithet.
Species Scientific Names
• Thus, the scientific name for each species,
referred to as the species name, is a
combination of the genus name and specific
epithet.
Homo sapiens
Homo = Genus, sapiens = “wise man”
Naming Organisms
Why do we need to
name organisms?
What is the name
of this organism?
Why do
scientists not
want to use
common
names?
The common name of many animals can be misleading.
Ceylon frogmouth
(Batrachostomus moniliger)
is a bird.
Killer whales
(Orcinus orca )are the
largest member of
the dolphin family.
Flying fish
(Parezocoetus mesogaster)
do not fly, but glide.
Seahorse
(Hippocampus zosterae) is
not a horse, but a
fish.
Why do scientist not use common names?
Confusing – more than one common name
Misleading – starfish is not a fish
Why use a
scientific name?
There is only one
scientific name
Felis concolor
Species Scientific Names
United States and England- Sparrow
Spain – gorrion domestico
Holland – huismus
Scientific name: Passer domesticus
Scientific Name
What language is used for the scientific naming?
LATIN
What are the 2 parts of the scientific name?
Genus (Latin for group)
general description
organisms share a major
characteristic
species
exact kind
only 1 kind of organism
within a genus
Recognizing Relationships
Tell me something about each of these
organisms.
Carnegiea gigantea
giant saguaro cactus
Nymphaea odorata
fragrant water lily
Canis familiaris
domestic dog
Peromyscus californicus common California mouse
Viola tricolor
three color pansy
Genus + species
names should be used when
referring to an organism.
Species name alone is not enough.
Drosophila melanogaster is a
fruit fly.
Thamnophis melanogaster is
a garter snake.
What is the correct
way to write the
scientific name?
drosophila melanogaster
Drosophila melanogaster
Drosophila melanogaster
D. melanogaster
* Always capitalize the Genus and not the species.
Why are scientific names in Latin?
1. Latin is no longer used in conversation.
2. It’s tradition.
3. Universal.
Worksheet:
Writing the Scientific
Names of Animals
COMMONNAME
Human
Dog
Spanish lynx
Tiger
Jaguar
Leopard
Bullfrog
Cameroon Toad
Houston Toad
Nile crocodile
Caiman
Jamaican boa
Puerto Rican boa
Jamaican iguana
Mona iguana
Desert monitor
Komodo dragon
Aquatic box turtle
Peregrine falcon
Piping plover
Audouin's gull
Relict gull
Tooth cave spider
GENUS
Homo
Canis
Felis
Panthera
Panthera
Panthera
Rana
Bufo
Bufo
Crocodylus
Caiman
Epicrates
Epicrates
Cyclura
Cyclura
Varanus
Varnaus
Terrapene
Falco
Charadrius
Larus
Larus
Leptoneta
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SPECIES
sapiens
familiaris
pardina
tigris
onca
pardus
catesbeiana
superciliaris
houstonensis
niloticus
crocodilus
subflavus
inornatus
collei
stejnegeri
griseus
komodoensis
coahuila
peregrinus
melodus
audouinii
relictus
myopica
SCIENTIFIC NAME
Homo sapiens
Canis familiaris
Felispardina
Panthera tigris
Panthera onca
P. pardus
rana catesbeiana
Bufo superciliaris
Bufo houstonensis
Crocodylus niloticus
Caiman crocodilus
Epicrates subflavus
Epicrates inornatus
Cyclura Collei
Cyclura stejnegeri
Varanus griseus
varanus Komodoensis
Terrapene coahuila
Falco peregrinus
Charadrius melodus
Larus audouinii
Larus relictus
Leptoneta myopica
Question 4
What is the difference between “classification”
and “taxonomy?”
Answer
Classification is the grouping of objects or
information based on similarities. Taxonomy is
the branch of biology that classifies and names
organisms based on their different
characteristics.
Question 5
What are the two parts that make up
binomial nomenclature?
Answer
Binomial nomenclature comprises a genus name
followed by a specific epithet.