Biomineralization of radiolarian skeletons

Abstract

Biomineralization of radiolarian skeletons is considered. The development of any skeleton is controlled by the previously formed organic matrix, which serves as a cast or mold of the shell to be formed and provides its development as a whole structure through interaction of the organic and mineral skeletal components. Theoretical and experimental investigation of the organic and mineral components of extant foraminiferal and radiolarian skeletons provide a basis for the development of a hypothetical model for skeletal biomineralization. It begins from the formation of small primary calcitic crystallites in the foraminiferal test or appearance of dense primary opal globules in the developing radiolarian skeleton. These particles are then deposited in the organic matrix enclosed in the living cytoplasmic envelope (cytokalymma). These primary biomineral particles are progressively grouped in the hierarchically interrelating ultrastructural skeletal units E, D, C, B, and A. The interaction of the mineral and biogenic factors occurs at five levels: molecular, nano-, ultra-, micro-, and macrolevels.