A: Food Chain

Correct Response

• Adds 2 correct organisms to food chain: crab – octopus OR crab – seagull OR crab – seal OR octopus – seal

Incorrect Responses

• Includes fish in food chain (no information about food source given in table).
• Other incorrect

B: Effect on Seaweed

Correct Responses

• Mentions that the seaweed will increase in number or size (because there are fewer limpets to eat it).
  • Examples:
    • There will be more seaweed.
    • It will not be eaten, so it will grow.
• Mentions only that the seaweed will not be eaten as much (or similar); no explicit statement of increase in population given.
  • Examples:
    • There won’t be anything to eat it.
    • Less of it will get eaten.

Incorrect Responses

• Mentions that the seaweed will die or decrease in number/size.
  • Examples:
    • It will also die.
    • There will not be as much.
• Mentions that the seaweed will be unaffected.
  • Examples:
    • The seaweed should be fine because all it needs is water and sun to live.
    • Nothing will happen to it.
• Other incorrect

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C: Effect on Other Organism

Correct Responses

• CRAB with statement that it will die or decrease in number (because there are fewer limpets to eat).
  • Examples:
    • Crab. It could starve.
    • Crab. They would die, too, because they eat the limpets.
• OCTOPUS with statement that it will decrease in number (because there are fewer limpets and/or crabs to eat).
  • Examples:
    • Octopus. It will die because it needs the limpets.
    • Octopus. If the crabs die from less limpets, then the octopus will not have much food.
• OCTOPUS, SEAGULL, or SEAL with statement that it will still survive (because it can eat other things).
  • Examples:
    • Seagull. I think it would still live because there are a lot of fish in the ocean.
    • Octopus. If the limpet dies the octopus would just eat more crabs.

Incorrect Responses

• Identifies an organism in their food chain but an incorrect effect based on food source(s).
  • Examples:
    • Crabs. They will increase.
    • Seal. Nothing will happen because the crab is in between the seal and the limpets.
    • Octopus. It will be OK because in my food chain it only eats crabs.
• Other incorrect

D: Effect of Seaweed Not Growing Well

Correct Responses

• Describes the effect on specific organisms showing evidence of energy flow from seaweed through the food chain.
  • Examples:
    • The limpets will die, then the crabs will die, then the octopus will die.
    • Without seaweed the limpets will starve, and then the crab would die.
• Describes that all of the organisms in the food chain will die or decrease in number since the seaweed is the first organism in the food chain (producer).
  • Examples:
    • All the organisms would die without the seaweed as food for the food chain.

Partial Responses

• States only that all organisms will be affected with no or inadequate description.
  • Examples:
    • It would affect everything.
    • Nothing would grow.
• States only that the limpets will die or decrease in number/size without mentioning the effect on other organisms.
  • Examples:
    • The limpets die because they need seaweed.
    • If the seaweed dies, the limpets will die.

Incorrect Responses

• Indicates that other organisms will not be affected.
  • Examples:
    • Nothing will happen to the octopus and seagull because they don’t eat seaweed.
• Other incorrect

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