About This Project

Winged propulsion usually requires a power stroke followed by a recovery stroke. A potentially more efficient design is used by the sea butterfly (pteropod), a critical food source of arctic vertebrates. This snail-like creature swims with wings that flap in a figure 8 pattern just like a fruit fly, but rolls over in its spiral shell so the every stroke is a power stroke! We will research the performance of this novel design, and from it develop a bioassay for the impact of ocean acidification.

Ask the Scientists

What is the context of this research?

In 2014, I spent 4 months in Antarctica funded by NSF to study the flight of the sea butterfly Limacina helicina. It is dissolving. Why? Because CO2 enters from the atmosphere and makes the sea acidic. Within 30 years, this delicate creature is predicted to go extinct in the West Antarctic Peninsula region. While I care that my students will see the demise of this tiny flying snail, I am more concerned about the fish, penguins, and whales that love to eat this delicious organism; those charismatic megafauna will have a hard time finding another food that is so protein-rich. What will the world look like? What else will disappear that supports our lives? Please limit your carbon usage.

What is the significance of this project?

Ocean acidification (OA) poses a serious threat, particularly to organisms that precipitate calcium carbonate from seawater. One organism with an aragonite shell that is a key to high latitude ecosystems is the pteropod. With OA, the pteropod shell will thin because the aragonite is highly soluble. As the shell thins, it changes the mass distribution and buoyancy of the animal, which will affect locomotion, and through it, all locomotion dependent behavior such as foraging, mating, predator avoidance and migratory patterns. The loss of these sentinels of anthropogenic increases in CO2 may result in an ecological shift since some pteropods are responsible for ingesting nearly half the primary production in the Southern Ocean.

What are the goals of the project?

Our interdisciplinary research relies on biological studies of the 3D swimming behavior of the pteropod mollusk Limacina helicina in their natural environments with fluid mechanics analyses of swimming hydrodynamics via 3D tomographic particle-image velocimetry and computational fluid dynamics (CFD). In this study we will: (a) determine how the L. helicina uses its “wings” (parapodia) to propel itself; (b) examine whether its locomotory kinematics provide efficient propulsion; (c) identify the factors that influence swimming trajectory and “wobble”; and (d) synthesize all data and insights into guidelines for the potential use of pteropod swimming behavior as a bioassay for OA and serve as an early warning of impending onset of OA effects on this important members of the plankton.