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. 2018 Aug 6;9:439. doi: 10.3389/fendo.2018.00439

Figure 1.

Figure 1

Sea urchin indirect life history. Major stages of the indirect life cycle of S. purpuratus during which skeletogenesis occurs. Post-hatching, the embryo grows larval arms, becoming a free-swimming pluteus larva. The pluteus feeds on plankton in the water column, accumulating resources for metamorphosis. Prior to attaining metamorphic competence, the larva grows a juvenile rudiment with skeletal structures necessary for survival as a juvenile, including adult spines and tube feet. Also pictured is the metamorphosed juvenile, and the adult sea urchin.