Question Sheet: Sea Giants and Island Pygmies


Before reading:

  1. What are the advantages and disadvantages of an animal being large?
  2. Give an example of how animals adapt to their environments.

During reading:

  1. What is the island rule, and how does it work?
  2. What happens to the typical size of snails in deep versus shallow water?
  3. Describe in your own words two possible explanations of why the island rule

    might be true.

  4. Why does McClain consider the food-based theory unique and useful?
  5. How has McClain’s research expanded the applicability of the island rule?
  6. What are McClain’s plans to continue his research in the future?

After reading:

  1. Why would variety in related species be evolutionarily logical and

    practical? See


  2. Why do you think McClain choose to study sea snails and not some other group of species? See

    (National Oceanic and Atmospheric Administration).

  3. Describe the ways in which the deep sea is evolutionarily similar to an

    island and how it is different.

  4. How do the illustrations in this article help you understand what the writer

    means? What other illustrations might be helpful?

  5. Might there be animals that are the same size on the mainland and on an

    island? Why would certain animals not vary in size?


On a map, locate an island where you can find pygmy elephants and another island where you can find giant rats. See and


  1. In the classic science fiction novel Twenty Thousand Leagues Under the


    , Jules Verne described a number of sea creatures that were an unusual

    size. What do such descriptions add to the story? Why are giant animals

    particularly interesting? See


  2. Jules Verne’s novel The Mysterious Island is a sequel to Twenty

    Thousand Leagues Under the Sea

    . What sorts of animals play roles in this

    book? Why does the author introduce them? See (Wikipedia).


A princess visits an island inhabited by two tribes. Members of one tribe always tell the truth, and members of the other tribe always lie. The princess comes to a fork in the road. She needs to know which road leads to the castle so as to avoid the fire-breathing dragon and rescue the prince from the wizard holding him captive in the castle. Standing at this fork in the road is a member of each tribe, but the princess can’t tell which tribe each belongs to. What question should she ask to find the road to the castle?