Study Summary: 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.
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.