Shellfish Breeding and Hatchery Management (2+1)

11.4.1 Comparison of larval development among the bivalves

In pearl oyster, pediveliger develops to plantigrade having a size of 200 µm. All along the margin except umbo region rapid shell growth takes place. Labial palps, additional gill filament and byssus threads develop. Plantigrade develops into spat (300µm). It is a juvenile having left valve larger than right valve.

In mussles, Veliger grows to umbo stage approximately 20h after fertilization. It develops a pedal organ and it is called pediveliger larvae. Spat settlement takes place from 20^th day onwards and continious for 5-9 days.

In clams, the different stages in the development is mostly similar to that of green mussles. The differences being that D- hinge veliger starts consuming food 1-3 days after fertilization in clam, Umbo becomes clearly visible 7-15 days after fertilization and settlement stage is 21-35 days after the date of fertilization.