STUDIES ON THE REPRODUCTIVE BIOLOGY OF RAPANA VENOSA

The reproductive habit , season and reproduct ive capacity , hatching, development and metamorphosis of larva, and development course of naiad and young Rapana venosa were studied in this paper. It s reproductive period is from June to August ( 19- 26 e ) every year in inshore of Shandong . The parents mate many times in a reproductive period. The female spawns 2. 1 times and lays 655. 9 egg bags in average every reproductive period. The individual reproductive capacity is 754 thousants in average. There are average 1149 zygotes in a egg bag. Under 21- 22 e , the religer larva hatched af ter 20- 26 days. Hatching rate is 80. 8% . After 26- 30 days, the larva developed into naiad and grew into young snail after 57 days.