Deep-sea macroplanktonic sea cucumbers: suspended sediment feeders captured from deep submergence vehicle.  Observations in situ confirm the swimming and feeding behavior in previously unreported dense assemblages of the holothurian Peniagone diaphana, at a depth of 2000 meters, off southern California. Proximate analysis of captured specimens indicates that this organism may represent a numerically significant, but low organic content member of many near-bottom deep-sea communities.