Statoliths as archives of cephalopod life cycle: a search for universal rules

The role of various hard structures of fish and cephalopods as living archives is briefly reviewed, and the role of the cephalopod statolith as an archive of age is treated in more detail. The statolith deposition hypothesis is considered as a complete validation tool (in contrast to the more common partial validation). The hypothesis emphasises the role of crystallisation stabilisers (such as Sr) early on, reaction switchers (such as pH) which are the deposition engines, and regulators-linkers (such as proteins) which control runaway crystallisation and are responsible for species-specific shapes and other individual details. Implications of deposition-oriented approach and research for understanding of growth and application of growth studies are also discussed.