1. Bell Work 1. What is the scientific name for the human species?
2. What do you think are the common names for Felis catus and Canis familiaris?
3. In each case what does the first name refer to?
4. What do the two names together stand for?
5. Which group, genus or species, is more inclusive?

2. Finding Order in Diversity

3. The Diversity of Life
Natural selection and other processes have led to a staggering diversity of organisms.
Biologists have identified and named about 1.5 million species so far.
They estimate that 2–100 million additional species have yet to be discovered.

4. Why do scientists classify organisms?
Biologists use a classification system to name organisms and group them in a logical manner → this is called taxonomy
Scientists use scientific names as a standard to aid communication → it acts as a common language that everyone understands

5. Assigning Scientific Names
Common names of organisms vary, so scientists assign one name for each species.
Because 18th century scientists understood Latin and Greek, they used those languages for scientific names.

6. Binomial Nomenclature
In binomial nomenclature, each species is assigned a two-part scientific name → scientific names are always written in italics (or underlined) and the first word is capitalized while the second word is lowercased
The first word in a scientific name is the genus to which the species belong; the whole scientific name is the species of the organism

7. Binomial Nomenclature
Examples:
Scientific Name Common Name
Homo sapiens Human
Ursus arctos Grizzly Bear
Ursus maritimus Polar Bear

8. Linnaeus’s System of Classification
Linnaeus’s system of classification is hierarchical→ which means it consists of levels
There are seven levels or taxa (taxonomic category; singular: taxon)

9. Linnaeus’s System of Classification
From most inclusive (general) to most specific of taxa are:
Kingdom → Phylum → Class → Order → Family → Genus → Species
Mnemonic devices can be used to remember the levels of classification

10. Genus and Species
Grizzly bear
Black bear

11. Family
Grizzly bear
Black bear
Giant panda

12. Order
Grizzly bear
Black bear
Giant panda
Red fox

13. Class
Grizzly bear
Black bear
Giant panda
Red fox
Abert squirrel

14. Phylum Grizzly bear Black bear Giant panda Red fox Abert squirrel
Coral snake

15. Kingdom Grizzly bear Black bear Giant panda Red fox Abert squirrel
Coral snake
Sea star

17. Linnaeus’s System of Classification
Possible mnemonic devices:
Kings Play Cards On Fat Green Stools
Keeping Precious Creatures Organized For Grumpy Scientists

18. Example of Human Classification:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Hominidae
Genus: Homo
Species: Homo sapiens