Large‐scale ciliary reversal mediates capture of individual algal prey by Müller's larva

We documented capture of microalgal prey by several species of wild‐caught Müller's larvae of polyclad flatworms. To our knowledge, this is the first direct observation of feeding mechanism in this classical larval type. High‐speed video recordings showed that virtually all captures were mediated by large‐scale transient ciliary reversal over one or more portions of the main ciliary band corresponding to individual lobes or tentacles. Local ciliary beat reversals altered near‐field flow to suck parcels of food‐containing water mouthward. Many capture episodes entailed sufficient coordinated flow disruption that these compact‐bodied larvae tumbled dramatically. Similar behaviors were recorded in at least four distinct species, one of which corresponds to the ascidian‐eating polyclad Pseudoceros canadensis.