intermolt

Intermolt is the phase in the molting cycle of many arthropods, especially crustaceans and insects, that occurs between successive molts. It is the period from the end of one postmolt stage to the onset of the next premolt stage. During intermolt, the animal typically grows by feeding, and the exoskeleton remains intact, though it may thicken as the organism increases in size.

In crustaceans, the intermolt period can be long and variable, influenced by species, temperature, food availability, and the animal’s energy reserves. Growth during this phase occurs primarily through feeding, while the existing cuticle provides protection as the animal stores energy and resources for the upcoming molt. The transition toward the next molt is marked by hormonal changes that prepare the animal for premolt, during which the old cuticle is detached (apolysis) and a new, secreted cuticle forms beneath it.

Regulation of the molt cycle involves neuroendocrine signals. In many crustaceans, molt-inhibiting hormone from the eyestalks helps maintain intermolt, while rising levels of molt-inducing hormones trigger premolt and the subsequent ecdysis (the actual shedding of the old cuticle). After molting, the organism enters the postmolt phase, during which the new cuticle hardens and may appear softer for a time before full sclerotization, after which intermolt resumes.

The concept of intermolt is used broadly across arthropods to denote the lengthy growth interval between molts. Its exact duration and physiological details vary by species and ecological context, but the core idea remains: intermolt is the period between molts when growth occurs and the organism prepares for the next shedding event.