THE UBIQUITY OF FLUORINE AMIDST THE TAXONOMIC AND MINERALOGICAL DIVERSITY OF ASCIDIAN SPICULES

Certain ascidian species, colonial or solitary contain calcareous spic ules in the tunic, in internal tissues or both. The mineralogy of thes e bioaccumulations has seldom been investigated. Many kinds of ascidia n spicules were analysed using several physical and chemical technique s, and their crystallochemical characteristics compared in a taxonomic review. Fluorine was always present regardless of the type of calcium salt found in the spicules. Comparative data from other marine invert ebrates are given. For the first time, the presence of calcium oxalate crystals is demonstrated in ascidians.