Food Chains, Food Webs, and the Transfer of Energy

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Food Chains, Food Webs, and the Transfer of
Energy

• Symbiosis and Succession too!

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Autotrophs

• A groups of organisms that can use the energy in
  sunlight to convert water and carbon dioxide into
  Glucose (food)
• Autotrophs are also called Producers because they
  produce all of the food that heterotrophs use
• Without autotrophs, there would be no life on
  this planet
• Ex. Plants and Algae

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Autotrophs
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Autotrophs

• Chemotrophs
• Autotrophs that get their energy from inorganic
  substances, such as salt
• Live deep down in the ocean where there is no
  sunlight
• Ex. Bacteria and Deep Sea Worms

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Heterotrophs

• Organisms that do not make their own food
• Another term for Heterotroph is consumer because
  they consume other organisms in order to live
• Ex. Rabbits, Deer, Mushrooms

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Heterotrophs
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Heterotrophs

• Consumers
• 1. Scavengers/Detritivores feed on the tissue
  of dead organisms (both plans and animals)
• Ex. Vultures, Crows, and Shrimp

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Heterotrophs

• Consumers
• 2. Herbivores eat ONLY plants
• Ex. Cows, Elephants, Giraffes

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Heterotrophs

• Consumers
• 3. Carnivores eat ONLY meat
• Ex. Lions, Tigers, Sharks

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Heterotrophs

• Consumers
• 4. Omnivores eat BOTH plants and animals
• Ex. Bears and Humans

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Heterotrophs

• Consumers
• 5. Decomposers absorb any dead material and
  break it down into simple nutrients or
  fertilizers
• Ex. Bacteria and Mushrooms

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Transfer of Energy

• When a zebra eats the grass, it does not obtain
  all of the energy the grass has (much of it is
  not eaten)
• When a lion eats a zebra, it does not get all of
  the energy from the zebra (much of it is lost as
  heat)

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Transfer of Energy

• The two (2) previous examples of energy transfer
  show that no organism EVER receives all of the
  energy from the organism they just ate
• Only 10 of the energy from one trophic level is
  transferred to the next this is called the 10
  law

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Trophic Levels

• Energy moves from one organisms to another when
  it is eaten
• Each step in this transfer of energy is know as a
  trophic level
• The main trophic levels are producers, consumers,
  and decomposers

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Food Chains

• The energy flow from one trophic level to the
  other is know as a food chain
• A food chain is simple and direct
• It involves one organism at each trophic level
• Primary Consumers eat autotrophs (producers)
• Secondary Consumers eat the primary consumers
• Tertiary Consumers eat the secondary consumers
• Decomposers bacteria and fungi that break down
  dead organisms and recycle the material back into
  the environment

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Food Chain
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Food Web

• Most organisms eat more than JUST one organism
• When more organisms are involved it is known as a
  FOOD WEB
• Food webs are more complex and involve lots of
  organisms

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Food Web
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Food Web

• Notice that the arrow points in the direction of
  the energy transfer, NOT what ate what

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Food Web
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Biomass

• The total mass of the organic matter at each
  trophic level is called biomass
• Biomass is just another term for potential energy
  energy that is to be eaten and used.
• The transfer of energy from one level to another
  is very inefficient (10 Law)

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Biomass
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Ecological Pyramid

• An ecological pyramid shows the relationship
  between consumers and producers at different
  trophic levels in an ecosystem
• Shows the relative amounts of energy or matter
  contained at each trophic level
• The Pyramid shows which level has the most energy
  and the highest number of organisms

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Ecological Pyramid
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Ecological Pyramid
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Ecological 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?

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Symbiosis

• A close and permanent association between
  organisms of different species
• Mutualism a relationship in which both
  organisms benefit from each other
• Example Birds eating pest off a rhinos back
• Commensalism a relationship in which one
  organism benefits and the other is not affected
• Example Barnacles on a whale
• Parasitism A relationship in which one organism
  benefits and the other is harmed
• Example Ticks on a dog

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In your Lab notebook complete the following
Symbiotic Relationship Textbook Definition My definition (less than 4 words) My example
Commensalism a relationship in which one organism benefits and the other is not affected
Mutualism a relationship in which both organisms benefit from each other
Parasitism A relationship in which one organism benefits and the other is harmed
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Ecological Succession Some Definitions

• the gradual and directional process of species
  change in a community
• biotic communities change through time in
  response to many influences
• climatic change
• disturbances
• invasion of species from other areas
• Eventually, succession leads to a climax
  community

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Primary Succession

• the processes and progress involved in changing
  an area from one lacking any community (no
  plants, no animals, no insects, no seeds, etc.)
  to one consisting of individuals, populations,
  communities, and ecosystems.
• the arrival of life in an area where no community
  previously existed.

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Example of Primary Succession
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Secondary Succession

• The arrival of new species in an area that
  already has life.
• Results in the transition of a community from
  pioneer species to climax species.
• Because soil may already be present, the rate of
  secondary succession is faster than primary
  succession.
• Secondary succession also indicates changes in
  community composition following disturbances.

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Example of Secondary Succession
This is an example of a secondary succession
following a disturbance (fire). It does not
completely wipe out life.
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What is a Pioneer Species?

• The first species to colonize an area (usually
  lichens and mosses but sometimes higher plants),
  beginning the process of soil formation.

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What is Climax Community?

• A community that remains fairly constant in
  species composition if the land and climate are
  undisturbed. These are the communities that
  characterize the various biomes.

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A summary of changes that occur during succession

• Pioneer species colonize a bare or disturbed
  site. Soil building.
• Changes in the physical environment occur (e.g.,
  light, moisture).
• New species of plants displace existing plants
  because their seedlings are better able to become
  established in the changed environment.
• Newly arriving species alter the physical
  conditions, often in ways that enable other
  species to become established.
• Animals come in with or after the plants they
  need to survive.
• Eventually a climax community that is more or
  less stable will become established and have the
  ability to reproduce itself.
• Disturbances will start the process of succession
  again.

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Food Web of Biome_____this is your title

• Choose a Biome from pg 99-104) to draw a food web
• Draw, Color and Label your Food Web
• Example on pg 71
• A food web shows how two or more food chains
  interact
• Must show arrows showing energy flow
• What eats what

• 4. Must label organisms as
• Method of nutrition
• Producer
• Herbivore
• Carnivore
• Omnivore
• Tropic Level
• Producer
• 1st Consumer
• 2nd Consumer
• 3rd Consumer
• Decomposer or Scavenger
• Dont forget about the SUN!