Miner B G, Sanford E, Strathmann R R, Pernet B, Emlet R B
Biol Bull. 1999 Aug;197(1):14-25. doi: 10.2307/1542993.
Larvae of two annelids, the opheliid Armandia brevis and the echiurid Urechis caupo, captured small particles between opposed prototrochal and metatrochal ciliary bands and also captured large particles with wide ciliated mouths. The body volume of larval A. brevis increased more rapidly than the estimated maximum clearance rate as segments were added. Capture of larger particles by late-stage larvae may compensate for this potentially unfavorable allometry. The existence of larvae that use two feeding mechanisms at once, not previously known in annelids, suggests possible evolutionary routes between larval forms that feed only with opposed bands (e.g., serpulids and oweniids) and those that use complex oral ciliature to feed primarily on large particles (e.g., polynoids and nephtyids). In particular, the metatroch and food groove of opposed-band feeders may have arisen as expansions of oral ciliation in ancestral large-particle feeders; alternatively, extensive oral ciliation in large-particle feeders may have originated as a modification of metatroch and food-groove cilia in ancestral opposed-band feeders.
两种环节动物的幼虫，即海蚯蚓科的短阿曼地亚蚯蚓（Armandia brevis）和螠虫纲的可口革囊星虫（Urechis caupo），在相对的原纤毛带和后纤毛带之间捕获小颗粒，并且还能用宽阔的具纤毛口捕获大颗粒。随着体节的增加，短阿曼地亚蚯蚓幼虫的身体体积比估计的最大清除率增长得更快。后期幼虫对较大颗粒的捕获可能弥补了这种潜在的不利异速生长。同时使用两种摄食机制的幼虫的存在，这在环节动物中以前并不为人所知，这表明了仅用相对的纤毛带摄食的幼虫形式（例如，龙介虫和欧文蚓）和主要用复杂的口纤毛结构摄食大颗粒的幼虫形式（例如，多鳞虫和海女虫）之间可能的进化途径。特别是，相对带摄食者后纤毛带和食物沟可能是作为祖先大颗粒摄食者口纤毛的扩展而出现的；或者，大颗粒摄食者广泛的口纤毛可能起源于祖先相对带摄食者后纤毛带和食物沟纤毛的一种修饰。
