抄録
Larval culture of the bivalve Barnea dilatata was attempted with artificially fertilized eggs obtained from adults collected on October 3, 1998, from Hayatsue Estuary off Kawasoe-machi, Saga Prefecture. After fertilization, eggs developed in one day to D-shaped larvae with an average shell length (SL) of 60μm. Larvae fed Chaetoceros gracilis grew to 417±66μm, and thereafter no further growth was observed. The cultures provided larvae with a maximum shell length of 490μm, which suggests that the pediveliger shell length was within the range of 400 to 490μm. Experiments revealed that during the process of metamorphosis to plantigrade, planktonic larvae may choose a substratum from the viewpoint of physical factors, e.g, grain size, although biological factors such as bacterial population in the mud flat may also be important. When pediveligers were exposed to mud collected from the flat, they initially swam actively but then started crawling on the mud. The transition from swimming to crawling behavior was reversible and an alternation of crawling and swimming back into the water column was repeatedly observed. Finally, larvae were observed to burrow into themud using their foot. The whole process from initial burrowing in the mud until completion of metamorphosis to plantigrade of the shell and foot took one day.
