Does germanium interact with radular morphogenesis and biomineralization in the limpet Lottia gigantea?

Specimens of Lottia gigantea were incubated in germanium enriched seawater [( Ge]/[Si] = 0.2-783) for 1-8 days. The siliceous radulae were examined histologically. No visible changes, degenerations or deformations were found in all 62 experimental radulae, although germanium is known to be a competitive inhibitor of silicon. In high concentrations, germanium was toxic to the limpets and killed them. Germanium was incorporated into the radular teeth in a distribution similar to silicon. Two suggestions are discussed for the apparent noninhibitory result.