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 Muller9s larvae of polyclad flatworm. To our knowledge, this is the first direct observation of feeding mechanism in this classical larval type. High-speed video recordings show that virtually all captures are 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 alter near-field flow to suck parcels of food-containing water mouthward. Many capture episodes entail sufficient coordinated flow disruption that these compact-bodied larvae tumble dramatically. Similar behaviors were recorded in at least four distinct species, one of which corresponds to the ascidian-eating polyclad Pseudoceros.