Development of the sea urchins Temnopleurus toreumaticus Leske, 1778 and Temnopleurus reevesii Gray, 1855 (Camarodonta: Temnopleuridae)

Background Sea urchin larvae near metamorphosis form an adult rudiment that is a complex of the juvenile structures. However, the details of the mechanisms that form the adult rudiment are unknown. The temnopleurid sea urchins Temnopleurus toreumaticus and Temnopleurus reevesii occur in Japan, but the development of their juvenile morphology has not been described. In this study, we observed their development by light and scanning electron microscopy to follow the adult rudiment formation and to consider the mechanisms of evolution of juvenile morphology in sea urchins.