TOPIC: ClassificationAIM: What is classification?

Thousands of years ago, people started to realize that there were many different groups

of living things. There were many different types of plants and animals. They started

organizing them into groups based on certain characteristics. This is called CLASSIFICATION.

Scientists have identified more than 2.5 million different organisms. And their job isn’t even close to being finished! Some biologists estimate that there may be at least 7 million different kinds of organisms living in tropical rain forests and in the depths of Earth’s oceans. No wonder why we need to classify!

What is classification?

•Grouping of organisms based on similarities in structure

What istaxonomy?

•Branch of biology that deals with classification

The First Classification Systems

Greek philosopher Aristotle, in 4th century BC, divided living things in 2 groups: Plants and Animals. He also placed animals into 3 groups according to how they moved (ones that flew, swam, walked). Birds and bats were placed into the same group even though they are quite different. This system was used for almost 2000 years. Around the 17th century scientists started to classify organisms in a more meaningful way (form and structure).

Today’s classification system is based on the work of Swedish scientist Carolus Linnaeus. He classified living things as plants or animals but grouped them according to similarities in form and structure. He used a system that consisted of groups within larger groups within larger groups.

Whatclassificatio

nsystem do

weuse?

•Carolus Linnaeus (1700’s)

•All organisms are divided into 5 Kingdoms and 7 levels of classification

Kingdom

Phylum

Class

Order

Family

Genus

Species

Largest groups

Smallest groups and most closely related to each other

Kings

Play

Chess

On

Fine

Green

Stools

Kingdom•5 kingdoms•Largest classification group

•Very diverse

Species•One kind of organism•Can produce fertile offspring with each other

Kingdom

Phylum Phylum Phylum Phylum Phylum Phylum

Naming organisms

Before Linnaeus developed his naming system, plants and animals were named by a series of Latin words that described the physical appearance of the organism. This was very confusing. For example, let’s look at the first name of the honey bee. Apis pubescens, thorace

subgriseo, abdomine fusco, pedibus posticis glabris utrinque margine ciliatus. This means “fuzzy bee, light gray middle, brown body, smooth hind legs that have a small bag edged with tiny hairs.” Linnaeus named it Apis mellifera which means “honey-bearing bee.”

How do we

nameorganisms?

•Carolus Linnaeus •Binomial Nomenclature

•Two-word system of identifying organisms

•Genus species•Examples:•Humans Homo sapiens

•Homo = Genus•sapiens = species

Humans = Homo sapiensKingdom Animalia

Phylum Chordata

Class Mammal

Order Primate

Family Homoide

Genus Homo

Species sapiens

Kingdom Animalia

Phylum Cordata

Class Mammalia

Order Carnivora

Family Canidae

Genus Canis

Species Lupus (the wolf)

Canis lupus

Dolphin Tursiops truncatus

Raccoon Procyon lotor

Fruit flyDrosophila melanogaster

DichotomousKey

•List of characteristics used to identify an organism

•Arranged in steps (2 statements at each step)