ABSTRACT
Podia on the oral surface and at the ambitus were seen vigorously collecting particles from the substrate. These particles were passed from podium to podium towards the food grooves. In the food grooves, food was loosely aggregated by mucus, passed to the mouth by podia, and ingested. The rate of particle collection and passage along the food grooves was much higher when diatoms were added to the substrate than it was with normal sand substrate. Ciliary current flows were marked with dyes and particles. On the aboral surface, flow was radial from the apex to the ambitus. In contrast, currents on the oral surface flow anterior to posterior. On both surfaces, ciliary bands are arranged with the long axis of the cilia perpendicular to the flow. Particles were seen being transported by aboral ciliary currents, but most were lost at the ambitus.
