The effect of food availability on development and phenotypic plasticity in larvae of the sea cucumber (Apostichopus japonicus)

Three food treatments (low, medium, and high) were used aiming to investigate potential for phenotypic plasticity in the sea cucumber Apostichopus japonicus. On day 5 and 7 after first feeding, the significant delayed development of larvae occurred in 2000 cells mL(-1) day(-1). Principal component analysis indicated that larvae in the low food group differed morphologically from others mainly due to long lateral maximum and depth on day 5, but individuals from three treatments were not morphologically distinct based on the first two components. The results presumably indicated that early-stage larvae responded to scarce food by development of undulating profiles and long sinuous bands, and thus increased the surface area of ciliated band for feeding at the expense of the delayed development of larvae. No significant difference in larval stages was observed by day 10, but 60% of total larvae in 15,000 cells mL(-1) day(-1) had greater than two hyaline spheres compared with 20 and 30% in 2000 and 30,000 cells mL(-1) day(-1). As the presence of hyaline spheres is indicative of metamorphic competence for sea cucumber, it is suggested that A. japonicus larvae in commercial culture should be fed 15,000 cells mL(-1) day(-1).