1. 18-1 Finding Order in Diversity
Photo credit: ©Gary Randall/Visuals Unlimited

2. 18-1 Finding Order in Diversity
Natural selection and other processes have led to a staggering diversity of organisms. Biologists have identified and named about ______________________. They estimate that 2–100 million additional species have yet to be discovered.

3. Why Classify?
What’s the point? To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner. In the discipline of taxonomy,

4. Assigning Scientific Names
Common names of organisms vary, so scientists assign one name for each species. Scientific names are always:
Homo Sapiens Toxicodendron radicans

5. Assigning Scientific Names
Carolus Linnaeus developed a naming system called: In binomial nomenclature, The scientific name is italicized.
Carcharodon carcharias
Phoenicopterus roseus

6. Linnaeus’s System of Classification
Linnaeus not only named species, he also grouped them into seven levels of categories.
From largest to smallest

7. Linnaeus’s System of Classification
Each level is called a ________, or taxonomic category. Species and genus are the two smallest categories.
Grizzly bear
Black bear
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

8. Linnaeus’s System of Classification
Genera that share many characteristics are grouped in a larger category, the ________.
Grizzly bear
Black bear
Giant panda
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

9. Linnaeus’s System of Classification
An _________ is a broad category composed of similar families.
Grizzly bear
Black bear
Giant panda
Red fox
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

10. Linnaeus’s System of Classification
The next larger category, the _______, is composed of similar orders.
Grizzly bear
Black bear
Giant panda
Red fox
Abert squirrel
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.
Class Mammalia

11. Linnaeus’s System of Classification
Several different classes make up a ____________.
Grizzly bear
Black bear
Giant panda
Red fox
Abert squirrel
Coral snake
PHYLUM Chordata
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.
Copyright Pearson Prentice Hall

12. Linnaeus’s System of Classification
The ________is the largest and most inclusive of Linnaeus's taxonomic categories.
Grizzly bear
Black bear
Giant panda
Red fox
Abert squirrel
Coral snake
Sea star
KINGDOM Animalia
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.

13. Grizzly bear Black bear Giant panda Red fox Sea star Abert squirrel
Coral snake
Linnaeus’s hierarchical system of classification uses seven taxonomic categories. This illustration shows how a grizzly bear, Ursus arctos, is grouped within each taxonomic category. Only some representative species are illustrated for each category above the species level.