Phallusia mammilata

Certain vertebrates have an astonishing ability to accumulate vanadium in their blood. For example, the ascidian seaworm Phallusia mammilata has a blood concentration of V up to 1900 ppm, which represents more than a millionfold concentration with respect to the sea-water in which it lives. The related organism Ascidia nigra has an even more spectacular accumulation with concentrations up to 1.45% V (i.e. 14 500 ppm) in its blood cells, which also contain considerable concentrations of sulfuric acid (pH 0). One possibility that has been mooted is that the ascidia accumulates vanadate and polyvanadate ions in mistake for phosphate and polyphosphates (p. 528). 

Langer, M., Giebing, T, and D Haese, J. (1998) Purification and fimctional characterization of an 85-kDa gelsolin from the ascidians Microcosmus sulcatus and Phallusia mammilata. Comp. Biochem. Physiol., 119B, 697-704. 

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