How Do Scientists Classify Life on Earth?

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How Do Scientists Classify Life on Earth?
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Life On Earth

• Scientists have identified approximately 2.5
  million species of organisms on Earth, but
  estimate that there may be as many as 10 million
  inhabiting the Earth!
• Of these organisms, the largest percentage are
  single-celled bacteria!

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Why Classify?

• It help us understand more about the diversity of
  living things on Earth
• To understand how organisms are related to one
  another and how they are different from one
  another.

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Who Invented the First System for Classifying
Living Things?

• Organisms were first classified more than 2,000
  years ago by
• Greek philosopher Aristotle. 
• He classified things as
• either Plant or Animal.

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Aristotles System

• He grouped animals into Land Dwellers, Air
  Dwellers, and Water Dwellers.
• Can you think of any problems with Aristotles
  system?

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The New System taxonomy

• The discovery of new living things (thanks to
  better scientific tools) has resulted in a new
  classification system.
• The science of classifying living things is
  called taxonomy.
• Scientists developed a a ranking system for
  classifying organisms consisting of groups within
  larger groups.
• Today we will learn about Domains Kingdoms.

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THE THREE DOMAINSAll living organisms are
organized into

• Eukarya Eukaryotes cells with a nucleus
• Bacteria Prokaryotes cells without a nucleus
• Archaea Prokaryotes cells without a nucleus

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EUKARYA DOMAIN

• Animal Kingdom
• Plant Kingdom
• Fungi Kingdom
• Protista Kingdom
• Most organisms that we can see and that we are
  familiar with are in the Eukarya Domain.

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Archaea and Bacteria Domains

• Archaea

• Bacteria

• No nucleus (prokaryotes)
• Microscopic cells
• Adapted to life in extreme environments
• Deep ocean thermal vents
• Hot springs
• Very acidic or salty water
• Bottom of the ocean
• Petroleum deposits deep underground
• Other planets???

• No nucleus (prokaryotes)
• Microscopic cells
• Some bacteria
• are decomposers in the food chain
• are used to make food (yogurt, cheese, etc.)
• produce antibiotics
• cause disease in humans and animals

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Plants

• Eukarya Domain
• Trees, grass, flowers, ferns and mosses are
  examples of plants
• Multicellular
• Cells have a Nucleus
• Make their own food using water, carbon dioxide,
  chlorophyll and light energy
• Cells have a boxy shape and contain a green
  chemcial called chlorophyll

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Animals

• Eukarya Domain
• Humans, Insects, Birds, Reptiles
• Multicellular
• Cells have a Nucleus
• Do not make their own Food
• Over 1,000,000 on the planet!

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Fungi

• Eukarya Domain
• Yeasts, mushrooms, and molds
• Multicellular
• Have a Nucleus
• Do not make their own food- they decompose other
  organisms

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Protists

• Eukarya Domain
• Parameca and Euglena are examples
• Mostly unicellular
• Have a Nucleus
• Some can make their own food, some cant
• Microscopic but larger than bacteria
• Have different shapes
• Most are able to move

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Bacteria

• Bacteria Domain
• Some are beneficial to humans (l. Acidohpilus)
• Some cause disease (e. choli)
• Unicellular
• No Nucleus
• Some can make their own food, some cant
• Microscopic

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