Food Chains _ Food Webs by lanyuehua


									Food Chains & Food Webs

      Chapter 1.2-1.5
                Food Chain
• Food chain:
  – a relationship of organisms that depend on
    each other for energy or food.
  – Arrows point in direction of energy flow
• EX: algae is food for fish which are food
  for squid which are food for sharks.
                  Food Web
• Food Web
  – a group of
    interrelated food
               Delicate Balance
• Diversity is key!
• Sometimes the removal of one species results in the
  collapse of the ecosystem
  – Ex: sea otter controls urchin population; if no sea otters,
    urchins overgraze and collapse ecosystem

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