Molluscan veliger larvae and some annelid larvae capture particulate food between a preoral prototrochal band of long cilia that create a current for both swimming and feeding and a postoral metatrochal band of shorter cilia that beat toward the prototroch. Larvae encountering satiating or noxious particles must somehow swim without capturing particles or else reject large numbers of captured particles. Because high rates of particle capture are inferred to depend on the beat of both ciliary bands, arrest of the metatroch could be one way to swim while reducing captures. Larvae in eight families of annelids arrest metatrochal cilia frequently during prototrochal beat, often over a large part of the metatrochal band and with the arrested cilia aligned near the beginning of the effective stroke. In contrast, metatrochs of veligers of gastropods and bivalves rarely arrested while the prototroch beat, and those arrests were more localized and variable in position. This difference in metatrochal arrest was unexpected under hypotheses of either a single origin of this feeding mechanism or multiple origins within each phylum. Although different in metatrochal arrests, larvae of both phyla can separate swimming from feeding while both prototroch and metatroch beat. One hypothesis explaining low rates of capture per encounter, without metatrochal arrest, is a change in adhesion of prototrochal cilia with algae. In a few observations, part of the velar edge was retained within the veliger’s shell so that exposed prototrochal cilia contributed to swimming while the adjacent metatroch and food groove were sequestered.

中文翻译：

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对比软体动物和环节动物幼虫的Metatrochal行为和游泳时的摄食调节

软体动物 veliger 幼虫和一些环节动物幼虫在长纤毛的口前原滑轮带之间捕获颗粒食物，该长纤毛为游泳和进食产生电流，而短纤毛的后尾纤毛带向原纤毛跳动。遇到饱食或有毒粒子的幼虫必须以某种方式游泳而不捕获粒子，否则会拒绝大量捕获的粒子。由于推测粒子捕获的高速率取决于两个纤毛带的节拍，因此捕获 metatroch 可能是游泳同时减少捕获的一种方式。八个环节动物科的幼虫在原滑轮搏动期间频繁地阻滞跖骨纤毛，通常是在跖骨带的很大一部分上，并且在有效中风的开始附近对齐被阻滞的纤毛。相比之下，腹足类和双壳类动物的 veligers 的 metatrochs 很少在 prototroch 跳动时停止，而且这些停止位置更加局部和可变。在这种喂养机制的单一起源或每个门内的多个起源的假设下，metatrochal 停滞的这种差异是出乎意料的。虽然metatrochal 逮捕不同，两个门的幼虫可以将游泳与进食分开，而prototroch 和metatroch 都跳动。一种解释每次遭遇捕获率低而没有发生原转子停滞的假设是原转子纤毛与藻类的粘附发生了变化。在一些观察中，部分软骨边缘保留在 veliger 的壳内，因此暴露的原滑轮纤毛有助于游泳，而相邻的原滑轮和食物沟被隔离。