The use of physicochemical properties to assess changes in the cuticle structure of crustaceans: Case of the prawn Palaemon serratus and its moult cycle

The crustacean cuticle is a composite material acting as a shell, but also linked with other physiological functions as respiration, locomotion or reproduction. The present study aimed to characterize for the first time the cuticle properties of the marine prawn Palaemon serratus using thermal (TGA) and chemical (FTIR, ICP-AES) techniques. The use of native lyophilized cutiles also enabled to estimate the complexity of the cuticle structure of P. serratus. Hence, the prawn cuticle was found to be composed of bound water at 14 %, Light macromolecules at 27 %, heavy macromolecules at 17 % and inorganic elements at 42 %. This composition appeared to be similar to that of other swimming crustaceans, suggesting an adaptation of the cuticle structure in line with the ecology of the species. Then, thermal and chemical techniques were applied to characterize the structure changes of the cuticle induced by i) the moult cycle and ii) formic acid treatment. The moult cycle influence assessment revealed that the physicochemical properties were mainly modulated during postmoult, reflecting both the cuticle mineralization and tanning. Then, formic acid treatment led to cuticle alterations, related to the dissolution of amorphous minerals, which were detected by TGA, FTIR and ICP-AES. With these results, the assessment of cuticle properties using a combination of thermal and chemical techniques appeared to be interesting to monitor changes in cuticle structure in a dynamical context.