Classification of Living Things Introduction. Aristotle Greek 4 th Century BC Animals by movement...

Classificationof Living Things

Introduction

Aristotle

• Greek• 4th Century BC• Animals by movement• Plants by size

John Ray

• English• 17th century• Goal was to collect, name,

classify all plants and animals in England

• Used internal anatomy• First to use the word “species”

Carolus Linnaeus

• Swedish

• 18th century

• Used similarities in structure

• Invented a 2 word naming system (binomial nomenclature)

Genus species

Modern System

• Groups according to basic traits• Gives a unique name to every kind of living

thing• Name is used universally (Latin or Greek)

• Common names can be misleading– Starfish– Puma, cougar, mountain lion

Classification

• Process of grouping organisms based on similarities

Taxonomy

• Science of naming and classifying organisms

• Naming of organisms should reflect the traits of the organisms

• The more characteristics two organisms share, the more closely related they are

• If 2 organisms share the same trait, they could share the same ancestor

Biological Relationships

• Living things evolve over time• Scientists try to discover how one species

evolved as compared with another• Species that share ancestors are grouped

together.

Biological Relationships

• Scientists compare a variety of traits– Size– Bone structure– Body shape

Sargassum Fish

Sargassum Seaweed

Sea Dragon Sea Horse

Animal

Algae

Same body shape

Fronds

Fish with

Leafy fronds

Physical Evidence

• Early scientists used their eyes and measuring devices as tools to compare

• Noted color, size, weight, how energy is obtained

• Later they used internal structure and appearance

• Used fossils to compare species of past with those of today

Physical Evidence

• Fossils can tell how extinct organisms moved, lived, ate.

• Physical evidence shows that all organisms are related by evolution.

• Lives west of Rockies• Solid black head• No white feathers

• Lives east of Rockies• Blue, black, and white head

Cyanocitta stelleri Cyanocitta cristata

Genetic Evidence

• DNA and computers can be used to compare components of one organism with another.

• Genetic evidence usually supports physical evidence, but not always.