Egg capsule structure and hatching mechanism of Ocenebra erinacea (L.) (Prosobranchia : Muricidae)

• Published in: Journal of experimental marine biology and ecology 1988-01, Vol.119 (3), p.269-283
• Main Authors: Hawkins, L.E., Hutchinson, S.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Capsule structure; Fundamental and applied biological sciences. Psychology; Hatching mechanism; Invertebrates; Marine; Mollusca; Ocenebra erinacea; Physiology. Development
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(88)90197-9

The structure, permeability to water and salts, and internal osmotic concentration of the egg capsules of the marine gastropod Ocenebra erinacea (L.) have been examined at various stages between deposition and hatching. The egg capsule of this species is composed of protein fibres arranged in four laminae, enclosing a protein-gel matrix containing developing embryos. Radio-tracer studies of intact capsules show them to be freely permeable to water and salts at all stages of embryonic development; thus, transfer to media of differing osmotic concentrations is quickly reflected in changes in the intracapsular osmotic concentration and by transitory weight changes. The lack of protection exposes embryos to the risk of osmotic shock or desiccation and embryonic mortalities can occur. Encapsulated embryos are shown to contain increasing amounts of proteolytic substances as hatching approaches. At hatching, these substances are apparently secreted into the gel matrix causing structural and osmotic changes in the capsule. These result in the expulsion of the mucus plug sealing the top of the capsule, thereby allowing the embryos to escape.