Pyramidellid Protoconchs, Eggs, Embryos and Larval Ecology: An Introductory Survey

Abstract

Abstract: Major papers on pyramidellid protoconchs, larval development, and larval ecology are reviewed, partly with illustrations. Larval shell coiling (including hyperstrophy and heterostrophy) is discussed. A-, B-, and C-type protoconchs are figured and distinguished. Those of species in the Baltic and northwestern France have been used to infer modes of larval development. The reliability of many of these inferences is questioned. Egg, embryo, and veliger morphologies, functions and terminologies are then discussed, including confusions of the terms “egg” and “capsule.” The pigmented mantle organ or gland (“PMO”) is briefly reviewed. Previously published data on the eggs and larvae of Brachystomia “scalaris” (Macgillivray, 1843), of“Turbonilla” cummingi Hori and Okutani, 1997, and of “Odostomia columbiana Dall and Bartsch, 1907”, are reviewed in detail with some new interpretations. In the first of these species, egg size variation is possibly salinity-induced and may cause variation in mode of develo...