Classification of

Organisms

Main Idea

*****Chapter 14***** Students should be able to:

* Understand why a classification system is important * Understand that there are a variety of ways to classify

organisms * Understand the origins of our modern classification system

Why Classify?

To study the great diversity of

organisms on earth, biologists

must give each organism a name.

But, a universal naming system

was needed to avoid confusion

caused by regional names.

Why Classify?

Taxonomy is the

discipline of classifying

and assigning each

organism a universal

name.

Early Naming Systems

The first attempts to classify organisms

was to describe the physical

characteristics in great detail.

This resulted in very long names like:

“Oak with deeply divided leaves that

have no hairs on their undersides and

no teeth around their edges.”

Binomial Nomenclature

This system, proposed by Carolus Linnaeus, is still in use today.

It is a two-word naming system.

Each species is assigned a two-part scientific name.

Binomial Nomenclature

A scientific name is always written in italics (or underlined), and the first word is capitalized and the second word is lowercase.

Homo sapien is the scientific name for humans.

(or Homo sapien)

Binomial Nomenclature

Homo sapien

The first part of a scientific name is the genus.

A genus is a group of closely related species.

The second part of the name is unique to each individual organism or the species.

8

Binomial Nomenclature

Question?

Do Ursus arctos and

Ursus maritimus belong

to the same species?

No, they are different

species.

Question?

Do Ursus arctos and Ursus

maritimus belong to the

same genus?

Yes, they both belong to

the genus Ursus.

System of

Classification

The classification system is

hierarchical, or consists of levels.

They are, from largest to smallest,

domain, kingdom, phylum, class,

order,family, genus, species.

Each level is called a taxon or

taxonomic category.

The 8 Taxa (plural for taxon)

Domain Did Do

Kingdom King Kentucky

Phylum Philip People

Class Cross Climbing

Order Over Over

Family For Fences

Genus Good Get

Species Spaghetti Shot

The Human Species

(Domain Eukarya)

Kingdom: Phylum: Class: Order: Family: Genus: Species:

Animalia (Animal in Latin)

Chordata (Spinal Cord) Mammalia (have mammary glands) Primates (two mammary glands) Hominoidea (bipedalism)

Homo (man)

Sapien (wise, knowing)

Section

18Lea-1

Grizzly bear Black bear Giant

panda

Red fox Abert

squirrel

Coral

snake Sea star

KINGDOM Animalia

PHYLUM Chordata

CLASS Mammalia

ORDER Carnivora

FAMILY Ursidae

GENUS Ursus

SPECIES Ursus arctos

Section 18-1

Least Specific

(least in common)

Most Specific

(most in common)

In the following few slides, you will find 14 different organisms, each of them labeled with a letter. In your groups, write down two main classifications (example red/green). Then place the corresponding letters under the correct classification.

The Classification Game!!

With your partner

For Example

These organisms have been classified by their color.

Red Green

ARE

YOU

READY!

I

B

H

L M

AD

F

C

N

G

E

K

J

One Possible Solution

Plants Animals

A

B

C

D

E

F

G

H

I

J

K

L

M

N

????

Did You Have

Problems??

There were actually several different ways to go about classifying these 14 organisms. You might have done color, shape, size, number of legs… the possibilities are endless. You might have encountered one or two that really did not fit into either of your two classifications, what should you do when this happens? Make a new classification of course! And this is what scientist have done as well through the years.

Cladistics

A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa

(Phylogenetic means evolutionary development or history)

Cladogram: an evolutionary “tree”

Cladogram

a diagram that shows

evolutionary

relationships among

organisms based on

shared derived

characteristics.

**Helps scientists understand how one lineage

branched from another in the course of evolution

Derived Characters

A unique trait

of a particular

group of

organisms that

appears in

recent parts of

a lineage but

not in older

members.

Common ancestor