Phenotypic plasticity of the ciliated band of seven species of echinoderm larvae, 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. However, phenotypic plasticity of the ciliated band has been studied much less in non-plueti and comparisons among classes are difficult since prior studies vary in methods. We sought to determine how the plutei and non-plutei compared in their expression of plasticity in the ciliated band using standardized conditions for seven species (four plutei, three non-plutei). We measured the length of the ciliated band and body length at three developmental timepoints, comparing larvae provided high (6000 cells ml⁻¹<em>Rhodomonas lens</em>) and low (1000 cells ml⁻¹) food rations.</p>