Ecdysis

Ecdysis is the process of molting the cuticle in many invertebrates of the clade Ecdysozoa. This process involves the periodic shedding of the outer layer of the integument (skin or exoskeleton). After shedding, the organism typically expands or grows and secretes a new, larger cuticle.

Ecdysis is a hormonally controlled process, primarily regulated by the hormone ecdysone. The process begins with the separation of the old cuticle from the underlying epidermis (apolysis). The epidermal cells then secrete enzymes that digest the inner layers of the old cuticle, resorbing some of the material. Simultaneously, the epidermis begins to synthesize a new cuticle beneath the old one.

When the new cuticle is sufficiently developed, the old cuticle splits open, typically along predetermined lines of weakness. The animal then emerges from the old cuticle (exuviae). This emergence process can be rapid and require considerable effort.

Following ecdysis, the new cuticle is often soft and pliable, allowing the animal to increase in size. The cuticle then hardens and provides support and protection until the next molt.

The number of molts an animal undergoes during its lifetime varies depending on the species and environmental conditions. In some species, ecdysis continues throughout life, while in others, it ceases after reaching adulthood.

Ecdysis is essential for growth and development in many invertebrates, allowing them to increase in size and shed damaged or worn-out exoskeletons. It also plays a role in metamorphosis in some species, such as insects, where the larval form molts into the adult form.