  This fluid dynamics video demonstrates the capabilities of an experimental
setup to visualize organisms burrowing in granular substrates. The setup
consists of a tank filled with 1mm soda-lime glass beads, backlit by halogen
lights. The walls can be moved such that the space bound by them can expand or
contract to fit various organisms. A recirculation system oxygenates and cools
the salt water that flows through the substrate. The video shows the burrowing
behavior of a razor clam (Ensis directus) and a quahog (Mercenaria mercenaria).
Both animals inflate their foot with blood, making the foot a terminal anchor
against which they pull their shell downwards. Deformation of the granular
substrate can be seen around the animals as they advance downwards.
