The shell of planktonic foraminifera, varying in complexity, is one of the most commanding visual aspects of their morphology. Shell morphology has been a primary characteristic in taxonomic categorization of species. Recent fine structural studies of the cytoplasm and internal shell wall composition have largely complemented and substantiated the merit of using the shell architecture in establishing taxa. The remarkable regularity of shell design, species specific geometric plan, and the orderly manner of its development during maturation of the organisms also stimulates intriguing questions about the cellular biological basis for the genetic control of its deposition and the cytoplasmic mechanisms mediating its construction. Shells of planktonic foraminifera are one of the most abundant and significant calcitic fossil remains used extensively in interpreting biostratigraphic facies, reconstructing ancient environments based on fossil evidence, and providing evidence for major climatic changes in geological time (e.g. CLIMAP, 1976). Consequently, a clear understanding of the biological processes involved in shell deposition and an elucidation of environmental factors influencing the form and chemical composition of the shell wall are of broad significance for micropaleontology, cognate disciplines in the earth sciences and in cellular biology.
KeywordsPorosity Siliceous Calcite Fractionation Proline
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