page_title: Ecdysis
section_title: Insects
hierarchical_section_title: Ecdysis / Insects
caption_attribution_description: Aeshna cyanea and Exuvie Deutsch: Blaugrüne Mosaikjungfer frisch geschlüpft mit Larvenhaut. Der gesammte Schlüpfvorgang dauerte von 09:51 Uhr bis 13:07 Uhr auf einem Acker-Schachtelhalm. English: Female Southern Hawker emerging from larva skin on an Equisetum stem. Français&#160;: Aeschne bleue juste sortie de son exuvie. Русский: Недавно превратившаяся самка коромысла синего (Aeshna cyanea) со шкуркой личинки
context_page_description: Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remnants of the old, empty exoskeleton are called exuviae.
  After moulting, an arthropod is described as teneral, a callow; it is "fresh", pale and soft-bodied. Within one or two hours, the cuticle hardens and darkens following a tanning process analogous to the production of leather. During this short phase the animal expands, since growth is otherwise constrained by the rigidity of the exoskeleton. Growth of the limbs and other parts normally covered by hard exoskeleton is achieved by transfer of body fluids from soft parts before the new skin hardens. A spider with a small abdomen may be undernourished but more probably has recently undergone ecdysis. Some arthropods, especially large insects with tracheal respiration, expand their new exoskeleton by swallowing or otherwise taking in air.
context_section_description: Each stage of development between moults for insects in the taxon endopterygota is called an instar, or stadium, and each stage between moults of insects in the Exopterygota is called a nymph: there may be up to 15 nymphal stages. Endopterygota tend to have only four or five instars. Endopterygotes have more alternatives to moulting, such as expansion of the cuticle and collapse of air sacs to allow growth of internal organs.
  The process of moulting in insects begins with the separation of the cuticle from the underlying epidermal cells (apolysis) and ends with the shedding of the old cuticle (ecdysis). In many species it is initiated by an increase in the hormone ecdysone. This hormone causes:
  apolysis – the separation of the cuticle from the epidermis
  secretion of new cuticle materials beneath the old
  degradation of the old cuticle
  After apolysis the insect is known as a pharate. Moulting fluid is then secreted into the exuvial space between the old cuticle and the epidermis, this contains inactive enzymes which are activated only after the new epicuticle is secreted. This prevents the new procuticle from getting digested as it is laid down. The lower regions of the old cuticle, the endocuticle and mesocuticle, are then digested by the enzymes and subsequently absorbed. The exocuticle and epicuticle resist digestion and are hence shed at ecdysis.
caption: Moulting (ecdysis) in southern hawker, Aeshna cyanea
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