Adaptive heterochronic plasticity in development of the arms and echinus rudiment of food-limited plutei

Plutei of the echinoid Paracentrotus lividus were reared with high and low concentrations of food. At low concentrations, the larval arms grew longer and the echinus rudiment developed later relative to the larval arms. These changes in larval development resulted in an increased length of the ciliated band that produces currents for feeding and swimming, an increased length of skeletal rods that may be defensive, and a decreased allocation of materials to juvenile structures that do not become functional until metamorphosis.