Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

1989

Journal

The Nautilus

Volume

103

Issue

1

First Page

24

Last Page

35

Abstract

Dimensions of the shell and provinculum distinguish Teredo novalis larvae from the larvae o[ other bivalve mollusks. In the present scanning electron microscopic stud) of shell and pallet morphology during early ontogenetic stages of this species, the characteristic teredinid provinculum, with two interlocking pairs of small teeth and a wide central loath and socket was well-developed in shells 90 μm long. Provinculurn length ranged from 44 to 51 μm during the larval period. Average lengths of provincular teeth of the left valve were 9.6 μm for the anterior tooth and 8.2 μm for the posterior tooth; in the right valve, lengths were 7.2 μm for the anterior tooth, 16.4 μm for the central tooth, and 6.6 μm for the posterior tooth. Larval shell height prior to metamorphosis was just under 230 μm.

Formation of a ligament pit preceded secretion of the dissoconch and development of the apophyses, condyles, and exterior denticulated ridges. Shell loss along the posterior margin of the right valve accompanied a shift in the axis of articulation from the dorsal to the posterior plane; subsequent secretion of the dissoconch restored bilaleral symrnetry. The initial triangular shape of the pallet blade became increasingly rectangular and finally elongate with growth along the distal margin.

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