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（echinoderms）的摄食幼体存在两种截然不同的形态：一类为长腕幼虫（plutei），涵盖海胆纲（echinoids）与蛇尾纲（ophiuroids），其体表带有支撑细长腕突的钙化骨骼杆，腕突着生有纤毛环（ciliated band）；另一类为非长腕幼虫形态（non-plutei），涵盖海星纲（asteroids）与海参纲（holothuroids），其纤毛环着生于不含骨骼杆的圆形组织叶上。现有研究表明，四类棘皮动物的摄食幼体均可根据食物投喂量调整自身纤毛环长度：低食物投喂组的幼体，其纤毛环长度与体尺寸的比值，高于高食物投喂组幼体。既往研究提示，每增加单位长度纤毛环所需的结构成本，长腕幼虫可能低于非长腕幼虫，这或会影响两类幼体在纤毛环长度上的表型可塑性（phenotypic plasticity）范围。

本研究通过对比8个物种（覆盖所有具有摄食幼体的棘皮动物纲，每纲至少1种）在发育早期两个时间点的幼体纤毛环长度与蛋白质含量，验证“长腕幼虫单位生物量可支撑的纤毛环长度高于非长腕幼虫”这一假说。