The Chiton Radula: A Model System for Versatile Use of Iron Oxides*

The major lateral radula teeth of chitons (Mollusca:Polyplacophora) are one of the hardest and most wear resistant biomineralized tissues known to date. Their hierarchical architecture makes ingenious use of magnetite and a variety of other biominerals. In this chapter, we review the current understanding of radula tooth structure and function, the role of the organic matrix into which the mineral is deposited, and the sequence of events that results in highly selective precipitation of iron oxide biominerals in precisely delimited micro-architectural units. We further point out gaps in our knowledge, and highlight new approaches to investigate the molecular mechanisms that underlie biological control over iron oxide phase transformations.