The science of describing, naming and classifying organisms Taxonomy The science of describing, naming and classifying organisms

Classification Putting things into orderly groups based on similar characteristics Classification is a PART of taxonomy.

Why Scientists Classify Things Helps make order of living things Makes it easier for scientists to answer questions How many known species are there? What are the defining characteristics of each species? What are the relationships between these species?

History of Classification Aristotle was the first person known to classify living things. Before the 1600s living things were classified as plants or animals. Two major problems with this classification scheme: Not very specific – animals and plants are 2 broad categories What about bacteria, archaebacteria, fungi, and protists?

History of Classification – cont. 1700s - Carolus Linnaeus founded modern taxonomy Taxonomy - the science of describing, naming and classifying organisms Binomial nomenclature – (bi=two, nom=name) Genus species Example: Homo sapiens = Humans Common name = Humans Specific name = sapiens Scientific name = Homo sapiens

The Old System – 5 Kingdoms

The New System - 6 Kingdoms Archaebacteria Eubacteria

The Newest System – 3 Domains

Modern Classification System Domain  Do Kingdom  Kings Phylum  Play Class  Cards Order  On Family  Fuzzy Genus  Green Species  Stumps

D DOMAIN KINGDOM PHYLUM CLASS ORDER FAMILY GENUS SPECIES

How Scientists Classify Things Scientists classify organisms based on SIMILAR characteristics Tools used to identify organisms Dichotomous keys Cladograms – branching diagram

Dichotomous Key 1a. Organism has 4 legs Go to # 2 Definition: identification aid that uses sequential pairs of descriptive statements What kind of animal is this? 1a. Organism has 4 legs Go to # 2 1b. Organism has more than 4 legs Go to # 20 2a. Organism has a tail Go to # 3 2b. Organism has no tail Go to # 35 3a. Organism has stripes Bengal Tiger 3b. Organism has no stripes African Lion

Cladogram Figure 2, p. 49 Definition: branching diagram that shows similarities and differences between species Which 2 animals are the least similar? Which 2 animals are the most closely related? Which animals give birth to live young?