SELECTIVE PRESERVATION OF CHITIN DURING THE DECAY OF SHRIMP

The preservation potential of chitin in the marine environment is a matter of debate. To determine the relative survival of chitin and other organic components, the shrimp Crangon was decayed under different laboratory conditions. Solid state C-13 NMR and Curie point pyrolysis-gas chromatography-high resolution mass spectroscopy demonstrated that slightly transformed chitin represents the major component of the remaining biomass after only eight weeks. This selective preservation confirms that the resistance of chitin to decay may be a major factor in accounting for the extensive fossil record of arthropods lacking a biomineralized skeleton. It also suggests that chitin is likely to be an important contributor to the organic content of recent marine sediments. The pyrolysate of the preserved cuticle of fossil shrimps reveals a homologous series of alkanes and alkenes indicating a substitution of chitin by more resistant organic matter derived from other sources.