ABSTRACT
Adult Actinopyga echinites (Jaeger) were collected from northern Taiwan (121°55’E,25°03’N) in summer. Some gonadal tubes were fixed in Bouin’s solution as the control. Other gonadal tubes were cut into pieces and set for 1 h (ovary-induced ova). The other oocytes were collected, bathed in 10−2M dithiothreitol (DTT) solution for 10 min and then in fresh seawater for 50 min (DTT-induced ova). The percentage of germinal vesicle breakdown at this three cases was 0.4% (the control), 6.4% and 84%, respectively. After artificial insemination, the embryos were cultured in seawater (ultraviolet light-irradiated, 35% S, 25–28°C) with the alga Isochysis aff. galbana at 104−5 cells/ml. Larvae developed from the ovary-induced ova grew to the auricularia with hydrocoele at the 13th day, to the doliolaria at the 18th day, to the pentactula with one podium at the 19th day after insemination. Pentactula settled on the substratum and became juveniles. The DTT-induced larvae developed slowly and took 15d, 20d and 21d, respectively to the above stages. The size of the ovary-induced larvae was larger than that of the DTT-induced ones, i.e., 1.13 mm vs. 0.62 mm at 17 days, and 0.78 mm vs. 0.37 mm after metamorphosis. At the 12th day, the body of ovary-induced larvae accumulated gradually light-yellow lipid spheres. The number of spheres is positively related to the size of larvae.
