Chapter 1Section 2

Classification

Why do we classify living things?

• Allows us to keep track of the 3 to 10 million different living things on Earth

• There have been many different ideas about how to classify living things– Classification: The systematic grouping of organisms

into categories on the basis of evolutionary relationships or physical appearance

• The Science of classifying is called “Taxonomy” • People have been classifying for nearly 2,000

years

Classification

– Carolus Linnaeus

– Father of “Taxonomy” – Developed systems for naming species and organizing

them into groups – Named over 4000 plants & animals – Used appearance to group species – Used binomial nomenclature – * His system is still the one we use today

Scientific naming• Binomial nomenclature is a system for

naming organisms with two-word scientific name:

• The scientific name is made up of the genus & species name• A genus, the first part of the scientific

name, is a group of similar species.• A species, the second part of the

scientific name, is a group of organisms that have similar traits and are able to produce fertile offspring.

Scientific naming

– What is Binomial Nomenclature?– “Binomial” = two-name – “Nomenclature” = naming system – Language: Latin – Ex: common house cat – Felis domesticus

Mountain lion, puma, cougar – Felis concolor Bobcat – Felis rufus

– The scientific name is made up of the genus & species name

Classification

• Organisms are now classified into one of three domains and then into one of six kingdoms.

Scientific naming• Every living thing has its own unique scientific

name based on the 7 levels of classification. These levels, from general to specific are:– Kingdom– Phylum– Class– Order– Family– Genus – Species

Scientific names

Classification tools

A dichotomous key is a series of descriptions arranged in pairs that lead the user to the identification of an unknown organism.

Classification tools

A cladogram is a branched diagram that shows the relationships among organisms, including common ancestors.