Final answer:
The procuticle of crustaceans is impregnated with calcium carbonate to enhance the strength of their chitinous exoskeleton.
Step-by-step explanation:
The procuticle of crustaceans is often impregnated with calcium carbonate. This substance is infused within the chitinous exoskeleton of many aquatic crustacean species, enhancing their protective qualities while also making them stronger than the exoskeletons of other arthropods.
Although the cuticle, which includes the procuticle layer, is primarily composed of chitin bound with protein, the addition of calcium carbonate increases the strength but can reduce flexibility. Crustaceans must undergo molting to grow, shedding their exoskeleton to allow for an increase in size or to progress to the next stage of development.