SPAWNING BEHAVIOR AND DEVELOPMENT OF PERINEREIS-NUNTIA VAR BREVICIRRUS (ANNELIDA, POLYCHAETA)

Perinereis nuntia var. brevicirrus was collected from a rocky shore at Qingdao, China, and cultured in the laboratory. Spawning heteronereid s occur with a semilunar periodicity about 2-4 days after full moon an d new moon in the field as well as in laboratory cultures. Both sexual partners emerge from their burrows and swarm at the water surface in the early morning. As typical in nereid species, a nuptial dance at th e water surface follows the encounter. While the male and female swim around each other in circles, gametes are released into the water. In P. n. var. brevicirrus, both eggs and sperms are connected within 2 th reads of mucus. During swarming, a gelatinous egg mass is shaped by th e circular swimming pattern of both sexual partners. To our knowledge this is the only nereid species producing connected gamete strings and a regular, formed egg mass. Embryos develop within greenish egg capsu les and hatch out at the nectochaete stage after 7-8 days in summer wa ter temperatures (21 degrees C to 23 degrees C), after 9-10 days at 18 degrees C, and after 2-3 weeks at 15 degrees C. No planktonic larval stages occur. Juvenile worms reach a length of 2-3 cm after 2 months.