Food Chains and Food Webs

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Food Chains and Food Webs

• Energy Flow in Nature

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What is an ecosystem?

• Ecosystem is a system of living things that
  interact with each other and with the physical
  world.
• A Biome is a collection of related ecosystems.

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What are some examples of ecosystems? What are
the characteristics?

• Desert
• Rainforest
• Ocean
• Taiga

• Tundra
• Grassland
• Deciduous Forest
• Wetlands

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Ecosystem Interactions

• An ecosystem can be as large as the Sahara
  Desert, or as small as a puddle!!!
• Ecosystems are more than just the organisms they
  contain. Geography,weather,climate, population of
  animals, and geologic factors also influence the
  interactions within an ecosystem.

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Energy Roles

• An organisms energy role in an ecosystem may be
  that of a producer, consumer, or decomposer.

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Producers

• An organism that can make its own food is a
  producer.
• Source of all food in an ecosystem.
• Capture energy from sunlight and stores it as
  food energy.

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Consumers

• Consumers are living things that cannot make food
  for themselves.
• A food chain contains several kinds of consumers,
  each of which occupies a different trophic level.
  
• (Herbivore, carnivores, omnivores)

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Decomposers

• Decomposers and scavengers break down dead plants
  and animals. They also break down the waste of
  other organisms. Decomposers are very important
  for any ecosystem. If they weren't in the
  ecosystem, the plants would not get essential
  nutrients, and dead matter and waste would pile
  up.
• There are two kinds of decomposers, scavengers
  and decomposers.
• Scavengers are animals that find dead animals
  or plants and eat them. While they eat them, they
  break them into small bits. In this simulation,
  flies, wasps and cockroaches are scavengers.
  Earthworms are also scavengers, but they only
  break down plants.
• Once a scavenger is done, the decomposers take
  over, and finish the job. Many kinds of
  decomposers are microscopic, meaning that they
  can't be seen without a microscope. Others, like
  fungi, can be seen.
• Different kinds of decomposers do different jobs
  in the ecosystem.
• Others, like some kinds of bacteria, prefer
  breaking down meat or waste from carnivores.

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Decomposers

• Help break down wastes and dead organisms and
  return the raw materials to the environment
• Bacteria and fungi

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Food Chains

• Series of events where one organism eats another
  and obtains energy.
• First organism in chain is the producer.
• The second organism is the consumer that eats the
  producer.

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PlanktonCrabSealOrca This is only one possible
chain in a marine ecosystem.
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Come up with an example to fill in the blocks of
a food chain in two different ecosytems.
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• Pass out the food web cards.

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• This organism is killed either by a natural (ex.
  Large storm or disease) or human cause (pollution
  or habitat loss).
• As that plant or animal drops out of the food web
  and lets go of the yarn, each person who feels
  the slack of the yarn lets go. Soon, the entire
  web has fallen to the ground all because one
  member of the food web was killed.

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Science Log Explain what would happen to the
food web if

• What do you think would happen if more than one
  organism in the food web was killed?
• What if the population of one animal increased
  suddenly?
• What if there were too many carnivores and few
  herbivores? Or, if there were too few carnivores
  and too many herbivores? What would happen to the
  food web?

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Oceans

• In oceans, as on land, there is a natural
  interconnection of creatures that forms a kind of
  food chain.
• Diatoms are microscopic plants that make their
  own food from sunlight.
• Zooplankton are tiny sea animals, such as krill,
  copepods, medusa jellyfish, and crab larvae.
• Small fish might include mackerel, herring, and
  basking sharks, as well as crustaceans (crab,
  shrimp, lobster), mollusks (clams, scallops) and
  squid.
• Large fish might include swordfish, tuna,
  octopus, and shark.
• Killer whales eat other whales and seals, as well
  as fish.
• Diatoms lt Zooplankton lt Small Fish lt Large Fish lt
  Killer Whales

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Food Webs

• Consists of many overlapping food chains in an
  ecosystem.
• Some organisms may play more than one role by
  changing consumer levels.

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What happens in a food web if one or more of the
organisms disappear?
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Which animals are carnivores and herbivores?
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What is the difference between a food web and a
food chain?

• FOOD WEBS show how plants and animals are
  connected in many ways to help them all survive.
  FOOD CHAINS follow just one path of energy as
  animals find food.

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Energy Pyramids

• A diagram that shows the amount of energy that
  moves from one feeding level to another in a food
  web.
• Represented in a triangle with the most energy at
  the producer level.

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Energy Ecological Pyramid
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Ecological Pyramid
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Ecological Energy Pyramid

• Which level has the most energy?
• Which level has the most organisms?
• Which level has the least organisms?
• Which level has the least energy?