TOPIC: Classification AIM: 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.

Less than 2 million have been classified so far! Scientists have identified more than 5-50 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! Less than 2 million have been classified so far!

Grouping of organisms based on similarities in structure What is classification? Grouping of organisms based on similarities in structure

Branch of biology that deals with classification What is taxonomy? 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.

All organisms are divided into 7 levels of classification What classification system do we use? Carolus Linnaeus (1700’s) All organisms are divided into 7 levels of classification

Phylum Class Order Family Genus Species Largest groups 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

5 kingdoms Largest classification group Very diverse Kingdom

Species One kind of organism Most specific way to classify an organism Can produce fertile offspring with each other Species

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.”

Binomial Nomenclature Two-word system of identifying organisms Carolus Linnaeus Binomial Nomenclature Two-word system of identifying organisms How do we name organisms?

Genus & species Examples: Humans Homo sapiens Homo = Genus sapiens = species

Humans = Homo sapiens Kingdom Animalia Phylum Chordata Class Mammal Order Primate Family Homoide Genus Homo Species sapiens

Canis lupus 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 flyDrosophila melanogaster

List of characteristics used to identify an organism Dichotomous Key List of characteristics used to identify an organism Arranged in steps (2 statements at each step) Workbook: page 175-176