Feeding Relationships

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Feeding Relationships

• Food Chains
• Food Webs
• Trophic Levels
• 10 Rule
• Biomass

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Food Webs
Food Webs Network of complex of feeding
relationships. Links all the food chains in an
ecosystem together. Trophic Levels Each step in
a food chain or food web. Each consumer depends
on the trophic level below for energy.
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Trophic Levels

• A step in a food chain or web is called a trophic
  level
• Producers(1st level) plants, trees, grass, algae
• Consumers (2nd 4th level)
• Primary grasshopper
• Secondary frog
• Tertiary snake

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Food Web Analysis

• Are there any primary consumers that can also be
  a secondary consumer?
• What would happen to the food web if -
• A) The harvest mice where to die off in the area?
• B) The algae died?
• C) The grasshopper died?

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Food Web

• Food web explains all of the feeding
  relationships at each trophic level in a
  community.
• A food web is more realistic than a food chain
  since most organisms feed on more that one
  organism.

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Food Web
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Food Chain
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10 Rule

• 10 Rule - as energy is transferred from one
  trophic level to the next
• 90 of the energy is lost as heat to the
  environment
• only 10 of the available energy is transferred
  to the next trophic level

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10 Rule
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Ecological Pyramids

• Ecological pyramids show the relationships in
  food chains and food webs.
• The bottom of the food pyramid represents the
  producers, the next level the herbivores, the
  next the 1st carnivore, and the next and/or top
  carnivore.

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Ecological Pyramids

• Ecologists recognize three different types of
  ecological pyramids
• energy pyramids
• biomass pyramids
• pyramids of numbers

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Energy Pyramid

• Shows the relative amount of energy at each
  trophic level

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Energy Pyramid
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Biomass Pyramid

• Biomass- The total amount of living organic
  matter at each trophic level.

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Biomass Pyramid
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Pyramid of Numbers

• Shows the relative number of individual organisms
  at each trophic level

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Pyramid of Numbers
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Ecological Succession

• Ecosystems are constantly changing in response to
  natural and human disturbances
• A series of predictable changes that occurs in a
  community over time is called ecological
  succession

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Primary Succession

• Primary succession is one type of ecological
  succession which occurs on land where no soil
  exists
• Example primary succession occurs on surfaces
  formed as volcanic eruptions create new land
  masses

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Secondary Succession

• Secondary succession is a result of a disturbance
  which changes an existing community without
  removing the soil
• Example secondary succession occurs when land
  cleared for farming is abandoned.