How does an arthropod form a new exoskeleton after molting?

To form a new exoskeleton, an arthropod undergoes a complex, hormonally controlled process known as molting or ecdysis.12

During the preparatory phase, the animal's underlying epidermis releases enzymes that digest the base of the old exoskeleton, specifically the endocuticle, allowing the old layer to separate from the body. While the old skeleton is still in place—a phase known as the pharate stage—the epidermis secretes a new, soft, and flexible cuticle beneath it.23

Once the old skeleton splits and the animal emerges, the new, larger cuticle is expanded by increasing internal blood pressure, often through the intake of air or water. The new exoskeleton then hardens through sclerotization, a process where proteins and chitin are stabilized by chemical cross-links. In crustaceans, additional rigidity is achieved by depositing calcium carbonate into the new procuticle. This hardening process can take hours, days, or even weeks to complete.231