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)