Post-Larval Development of the Tellinacean Bivalves Abra Alba, Tellina Fabula and Donax Vittatus (Mollusca: Bivalvia), With Reference to the Late Larva

Abstract

The post-larval shell and hinge development of the bivalves Abra alba (Wood), Tellina fabula Gmelin and Donax vittatus (da Costa) from the recently metamorphosed size to a juvenile size of 1·2–1·4 mm shell length has been examined using scanning electron microscopy. Early post-larval development in the stages up to 1·0–1·2 mm size can involve considerable morphogenetic change and requires careful description with photographic developmental series. The form of the pediveliger larva is present in the early post-larval shell and confirms the identity of the larvae of A. alba and T. fabula. The veliger and pediveliger larvae of A. alba are described. The similar larval form of the tellinacean bivalves is modified by differential margin growth early in post-larval development. Comparison of these bivalves with allied species reveals that the post-larvae are distinguishable at even the smallest sizes by the shell and hinge form. The metamorphic size of A. alba ranges from 0·26 to 0·31 mm, of T. fabula from 0·25 to 0·28 mm and of D. vittatus from 0·25 to 0·35 mm. The bivalve post-larvae were collected from the shallow sublittoral of Oxwich Bay, Bristol Channel, U.K., and the larvae from the overlying waters, during the years 1980–2.