Chapter 18 Taxonomy- branch of biology that groups & names organisms Earth is home to millions of different kinds of organisms. Each of these organisms share some common features with every organism To help understand and organize information about living things, scientists have created a system for classifying them into groups.

The Greek philosopher, Aristotle, developed the first method of classification He divided everything into 2 groups: Plants- herbs, shrubs, trees Animals- aquatic, terrestrial, aerial However, his system did not work. Why?

How Organisms are Classified Today The 8 Taxa Organisms are grouped into a series of categories called taxa, each one larger than the previous one. As you move down the list, each level becomes more specific & includes fewer members than the level above it. 1. Domain 2. Kingdom 3. Phylum 4. Class 5. Order 6. Family 7. Genus 8. Species

Classification of the Domestic Dog Kingdom Animal Dog, human, insect, worm, any animals Phylum Chordata Dog, human, fish, other backboned animals Class Order Mammal Carnivora Dog, human, whale, all other mammals Dog, wolf, lion, bear Family Canidae Dog, wolf, fox Genus Canis Dog, wolf Species familiaris Dog

Binomial Nomenclature- 2 part naming system In the 1700’s, Swedish botanis Carolus Linnaeus created the binomial nomenclature naming system still used today It gives each kind of organism a two-part name, the first part of an organism’s name identifies the genus The second part of the name identifies the species

Domains & Kingdoms Domains Kingdoms Characteristics Bacteria Eubacteria Single-celled prokaryotes; oldest organisms on Earth Archaea Archaebacteria Single-celled & don’t have peptidoglycan in cell walls Eukarya Protist, Fungi, Plant, Animal All are eukaryotes

Domain Eukarya Protist Single or Multi Cells have a nucleus Kingdom Cell number Cell characteristics Organisms Protist Single or Multi Cells have a nucleus Algae, protozoa Fungi Single or multi Cells have a wall & nucleus; no chloroplasts Yeast & mushrooms Plants Cells have a wall, nucleus & chloroplasts Moss, ferns, trees, flowering plants

Domain Eukarya Animals Multi Cells have a nucleus, but no wall or chloroplasts Sponges, worms, insects, mammals, fish, amphibians, reptiles & birds