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Early Ontogeny of the Septibranch Bivalve Cardiomya Pectinata (Carpenter, 1865)
Published online by Cambridge University Press: 11 May 2009
Extract
A minor spawning event by laboratory-held specimens of the septibranch bivalve Cardiomyapectinata yielded approximately 40 developing embryos. Their early ontogeny was observed from the early gastrula stage of development until the developing shell had completely enclosed the embryos and had attained 90% of the prodissoconch size observed on juvenile shells. Available evidence indicates that this species undergoes a non-planktotrophic, direct pre-juvenile development. Support for this view includes the enclosure of the developing embryo in a negatively buoyant, adhesive capsule until an advanced stage of development; poorly developed velar ciliation and lack of prodissoconch II formation. Although incomplete, this, the first study on septibranch pre-juvenile development, reveals that C. pectinata embryos form an external calcified shell in a manner homologous to the lamellibranch bivalves, and develop a velum modified for yolk storage, while lacking the epithelial test or pericalymma characteristic of protobranch bivalves. These data indicate that cuspidariid septibranchs are phylogenetically closer to the lamellibranchs than to the protobranch bivalves.
- Type
- Research Article
- Information
- Journal of the Marine Biological Association of the United Kingdom , Volume 66 , Issue 4 , November 1986 , pp. 943 - 950
- Copyright
- Copyright © Marine Biological Association of the United Kingdom 1986