Subject: A Heart Urchin (sp.?) is burrowing itself in the sand. This heart shaped relative of sea stars and sea cucumbers does so by using the spines on the side of its body and its tube feet underneath. These tube feet are liquid-filled hollow skeletons, regulated through the interaction between a muscular cover and an internal fluid pressure. Muscles in the tube wall allow the sea urchins to bend or retract their feet, while increased hydrostatic pressure is used to elongate the feet.
Technique: In post-production this footage was accelerated three times to keep the audience engaged.