Asteroids are deuterostomes. Fertilized eggs develop into bilaterally symmetrical planktonic larvae, which have 3-part paired coeloms. Embryonic coelomic structures have specific fates as the bilaterally symmetrical larvae metamorphose into radially symmetric adults. Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones. After settling, the larvae go through a sessile stage and metamorphose.
Development - Life Cycle: metamorphosis