The nonfeeding planktonic larvae of marine invertebrates typically lack larval feeding structures. One puzzling exception to this generalization is the annelid clade Sabellidae, in which nonfeeding larvae possess ciliary bands (specifically, food groove and metatroch) that, to the best of our knowledge, have no function other than in feeding. Nishi and Yamasu (1992b, Bulletin of the College of Sciences, University of the Ryukyus, 54, 107–121) published a scanning electron micrograph showing that nonfeeding larvae of the serpulid annelid Salmacina dysteri also possess food groove and metatrochal cilia. Here I demonstrate that nonfeeding larvae of Salmacina tribranchiata also bear ciliary bands identifiable as food groove and metatroch by position. High‐speed video of ciliary beat patterns shows that, together with the prototrochal cilia, these bands function in an opposed band system. The presence of feeding structures in nonfeeding annelid larvae is thus more widely distributed than previously recognized. The presence of feeding structures may make evolutionary transitions to planktotrophy more likely, and may underlie an inferred origin of larval feeding in the common ancestor of one of the two major clades of serpulid annelids, Serpulinae.

中文翻译：

---

相反的纤毛的带状在serpulid annelid Salmacina tribranchiata的非喂养幼虫

海洋无脊椎动物的非摄食浮游幼虫通常缺乏幼虫摄食结构。这种笼统的一个令人费解的例外是无刺幼虫蛛形纲，其中不喂食的幼虫具有睫状带（特别是食物沟和滑行），据我们所知，除喂食外，它们没有其他功能。西和Yamasu（1992年b，的科学学院的通报，琉球大学，54，107-121）发表的扫描电子显微照片表明该serpulid环节动物的nonfeeding幼虫Salmacina dysteri还具有食品槽和metatrochal纤毛。在这里，我证明了Salmacina tribranchiata的非喂养幼虫还具有可被识别为食物凹槽和位置变位的睫状带。纤毛节律模式的高速视频显示，这些带与原肌纤毛一起在相反的带系统中起作用。因此，与以前认识到的相比，在非饲喂圆环幼虫中饲喂结构的分布更为广泛。饲养结构的存在可能使向浮游生物的进化过渡更加可能，并且可能是推测的幼虫取食起源的基础，而幼虫取食是在蛇蝎子的两个主要进化枝之一的蛇形藻的共同祖先中。