In Crustacean's moulting meaning of "Anecdysic cycle" is:

Question

Accepted Answer

The correct option is 2: Intermoult is long and premoult is short.

The life cycle of a crustacean is defined by cyclical shedding of its rigid exoskeleton, known as moulting or ecdysis. The **Anecdysic cycle** describes a specific, hormonally-controlled pattern of this cycle, typically observed in crustacean species that moult infrequently, such as once a year, or in response to seasonal environmental changes. The term 'anecdysic' itself highlights the protracted nature of the intervening stage. Its key characteristic is a very long **Intermoult (Anecdysis)** phase, which is a period of metabolic quiescence and growth where the animal is waiting for the appropriate external or internal signal to proceed. This long intermoult is followed by a comparatively short and abrupt **Premoult (Proecdysis)**, the stage of rapid physiological preparation leading up to the shedding of the old shell.

The incorrect option is 1: Intermoult is short and premoult is long.
This is essentially the reverse of the anecdysic cycle. A pattern of a short intermoult suggests continuous or frequent moulting, typically seen in rapidly growing juvenile or small crustacea. In these cases, the cycle is primarily driven by somatic growth rather than environmental cues. The premoult phase, though long in this description, is energetically costly, and a short intermoult followed by a long premoult is not the defining feature of the anecdysic cycle type.

The incorrect option is 3: Intermoult and premoult are of same duration.
In the established classification of crustacean moult cycles (anecdysic, diapausal, and continuous), no type is defined by a perfectly equal duration between the intermoult and premoult stages. The premoult is a period of intense metabolic activity, consuming energy for apolysis and new shell formation, while the intermoult is relatively quiescent. Due to these drastically different physiological demands, the two periods rarely, if ever, occupy the same length of time, especially in a slow, environmentally-cued cycle like the anecdysic type.

The incorrect option is 4: Formation of new exoskeleton is incomplete and needed ecdysone hormone for completion of exoskeleton.
This statement describes a process that occurs *within* the moult cycle, specifically the initial stages of **Premoult (Proecdysis)**, and highlights the function of the main moulting hormone, **ecdysone**. While ecdysone is essential for initiating and completing the new exoskeleton formation, this general physiological description applies to all moult cycles. It defines the mechanism of the premoult stage, but it does not specify the unique temporal characteristic (long intermoult, short premoult) that defines the Anecdysic cycle *type*.