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Travel to the Woods Hole Oceanographic Institute in Massachusetts, where scientists study the microscopic world of the pteropod, more commonly know as the sea butterfly.

Nicknamed for the way it swims through the water, the sea butterfly propels itself with fins that protrude from its transparent shell and flap like a butterfly’s wings.

Though no larger than a grain of sand, these otherworldly creatures are a staple in the diet of marine animals like the sea angel. But the sea butterfly–and the predators that call it dinner–is in danger from the changing chemistry of our warming oceans. Ocean acidification dissolves the pteropod’s shell, often killing the animal.

Join Ari Daniel Shapiro as he delves into the delicate ecosystem of the sea butterfly. 

Strategies for Using EOL Podcasts in a Variety of Learning Environments

  • Have students write down terms they are unfamiliar with while listening to the podcast. After listening to the podcast, discuss and define them as a group.
  • Have students close their eyes and visualize what is being discussed in the podcast. Then have them produce a sketch based on their interpretations. 
  • Have students preview several Encyclopedia of Life podcasts and choose the one they find most interesting. Ask students to research the species or species group and present to their peers. 
  1. Why is the sea butterfly’s shell in danger?

    • Answer

      Increasing ocean acidification is dissolving the shells of the sea butterfly. Without a shell sea butterflies—and animals like fish and seabirds that rely on it for food—struggle to survive.

  2. Why are scientists concerned with the fate of an organism that is invisible to the naked eye?

    • Answer

      The tiny pteropod might not seem connected to global climate change. But the sea butterfly’s disappearing shell is a result of increasing ocean acidification that is caused by rising levels of carbon dioxide—a potent greenhouse gas—in the earth's atmosphere.

  3. Why does Cornelia Kavanagh create statues of the sea butterfly?

    • Answer

      Kavanagh loves recreating the beauty of the sea butterfly, but her exhibit is also meant to shed light on the troubled existence of the invisible creature. If people do not know about about pteropods, Kavanagh worries, "how many people are gonna care?"


region at Earth's extreme north, encompassed by the Arctic Circle.


scientist who studies living organisms.

carbon dioxide

greenhouse gas produced by animals during respiration and used by plants during photosynthesis. Carbon dioxide is also the byproduct of burning fossil fuels.


all related food chains in an ecosystem. Also called a food cycle.


to emit light.


very tiny living thing.


very small.

ocean acidification

decrease in the ocean's pH levels, caused primarily by increased carbon dioxide. Ocean acidification threatens corals and shellfish.


having to do with the Earth or dry land.