Trongylocentrotus Purpuratus
Sea urchins have 5 gonads that are located in the interambulacral region. Each gonad has a duct rising out of it which emerges from the gonopore which lies in the urchin's anal region. The urchin's gonads has special muscles which enable it to propel gametes out of its body. The sea urchin starts to release gametes from its body during breeding season in the spring months of a tropical climate. Sea Urchins will spawn in the Ocean. The male ejaculates sperm. Likewise, the female will ejaculate eggs. the eggs are fertilized in the open ocean. the urchin larvae hatches from its eggs with 4 arms. In the weeks to follow it will grow more arms until he has 8 arms (the rate of speed in which its arms grow is determinned by external factors). By the time the urchin has 8 arms, it begins to show mature features. Shortly after the growth of the 8th leg, spines and tubefeet protrude out of the urchin.