Figure 5

The inner ciliated band beats outward after prey capture. (A) SEM of fractured pilidium at the two-pairs-of-discs stage, exposing inner surface of one lappet (la) and buccal funnel (bf). Just inside the primary ciliated band (pcb), the inner ciliated band (icb) lies flat in most fixed larvae. This band is distinguished from the buccal ridge (br) by the offset at the margin between the lappet and the buccal funnel (dashed lines run along the bases of cilia in each band). cd = cephalic disc; st = stomach. (B) Two frames from Additional file 6: Video 6, before and after capture (times relative to lappet movement); larva in frontal view. Here the upper lappet moves as a cell is captured far out of focus. Both lappets activate the inner ciliated band and pause the primary band, as indicated by the recovery strokes. (C) Kymograph made by straightening the dotted line from the second frame of panel B. Traces show speed and beat orientation of ciliary tips. Dashed lines indicate times of frames of panel B. In the upper portion, the inner band (left side) shows no directed beat – traces meander like strands of wet hair – while the primary ciliary band beats strongly; the traces switch within ~15 ms near the middle of the sequence, such that the inner band beats out while the primary band stalls. Arrowheads indicate traces of two non-beating cilia, one within the inner band and one within the primary band, at the top of the kymograph. (D) Frames from a capture sequence (Additional file 7: Video 7) featuring a sustained barricade made by the inner ciliated bands. Times are relative to motion of the lappets. This pilidium transiently drops the barricade (frame 5), perhaps in response to another prey item passing within reach.