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?

Finding Order in Diversity

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.

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

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.

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

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

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)

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

Genus and Species Grizzly bear Black bear

Family Grizzly bear Black bear Giant panda

Order Grizzly bear Black bear Giant panda Red fox

Class Grizzly bear Black bear Giant panda Red fox Abert squirrel

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

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

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

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