Quantification of ciliated band length per unit protein in early echinoderm larvae (biometirc data), collected between 2020 and 2022 in the laboratory at California State University, Long Beach.

<p><strong>Study Summary: </strong>The feeding larvae of echinoderms take two distinct forms: plutei (echinoids, ophiuroids), which have calcified skeletal rods supporting long, slender arms bearing the ciliated band, and non-plutei (asteroids, holothuroids), where the ciliated band is borne on rounded lobes of tissue that do not contain skeletal rods. Feeding larvae of all four classes of echinoderms are known to alter the length of their ciliated bands in response to food ration, with larvae fed low rations producing longer ciliated bands relative to body size than larvae fed high rations. Prior work suggests that the structural cost of adding a given length of ciliated band might be lower for plutei than for non-plutei, which might affect the scope for phenotypic plasticity in ciliated band length in the two types of larvae.</p> <p>In this study we test the hypothesis that plutei and support a greater length of ciliated band per unit biomass than non-plutei by comparing ciliated band length and protein content of larvae of eight species (with at least one species from each echinoderm class that includes feeding larvae) at two timepoints in early development.</p>研究概述：棘皮动物（echinoderm）的摄食幼虫存在两种截然不同的形态：一类为羽腕幼虫（plutei），涵盖海胆纲（echinoids）与蛇尾纲（ophiuroids），其具有钙化骨骼杆（calcified skeletal rods）支撑细长附肢，附肢表面附着纤毛带（ciliated band）；另一类为非羽腕幼虫（non-plutei），涵盖海星纲（asteroids）与海参纲（holothuroids），其纤毛带附着于不含骨骼杆的圆形组织叶上。目前已知，四类棘皮动物的摄食幼虫均会根据饵料水平调整纤毛带长度：投喂低饵料量的幼虫，其纤毛带相对于体型的长度要高于投喂高饵料量的幼虫。已有研究表明，羽腕幼虫每增加单位长度纤毛带所需的结构成本可能低于非羽腕幼虫，这或会影响两类幼虫在纤毛带长度上的表型可塑性（phenotypic plasticity）范围。 本研究通过测定8个物种（覆盖所有具有摄食幼虫的棘皮动物纲，每个纲至少选取1个物种）在发育早期两个时间点的幼虫纤毛带长度与蛋白质含量（protein content），验证「羽腕幼虫相较于非羽腕幼虫，可在单位生物量（biomass）上支撑更长的纤毛带」这一假说。