CHANGES IN DECAPOD CUTICLE CHEMISTRY IN THE PRESENCE OF VOLCANIC ASH

Multiple specimens of decapod crabs were studied from Washington, USA, and from Chile, South America. These specimens were embedded in sediment that is hypothesized to contain volcanic ash. Subsequent sedimentary analysis of the samples demonstrated that the sediment encapsulating the crab specimens was comprised of some volcanic ash. The specimens were examined through thin sections and then analyzed using a scanning electron microscope (SEM) and Energy Dispersion Microscopy (EDS) to determine the chemical composition of the crab cuticle and the surrounding ash. This was then compared to pure volcanic ash and a control sample of crab cuticle not embedded in volcanic ash in order to determine if preservation in volcanic ash changed the chemical composition of the crab cuticle. The exceptional preservation of the crab cuticle is proposed to be a result of the presence of ash in the concretions, modifying the geochemistry of fossilization.