Larval development of the queen scallop, Equichlamys bifrons

Abstract

The smallest length of pelagic larvae of E. bifrons reared from fertilized eggs (mean diameter 119.6 pm) was 150 pm. Shell growth revealed insignificant umbone development, and the length-width relationship is described by the geometric mean regression:

w = 0.751l+20.720.

Eye spots were conspicuous and common in larvae of 165-175 pm length; metamorphosis generally occurred when larvae were just longer than 200 pm. In cultures maintained between 14 and 18°C juveniles were present 17-20 days after fertilization. Provinicular structure was simple, and there were generally four teeth at each end of the hinge.

Unisexuality, the large size of eggs and early larvae, shorter larval life, and the lack of umbone development are the most significant characteristics distinguishing the development of E. bifrons from that of Pecten meridionalis, another local pectinid.