Molting

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The two-hour process of imaginal molting in a cicada in fast motion . Cicadas belong to the hemimetabolic insects .
Butterflies are one of the holometabolic insects in which the caterpillars shed their skin several times as they grow.

The skinning (also Ecdysis , Ekdysis [of ancient Greek ἔκδυσις ékdysis "das) creeping out ("] or Apolyse [ancient Greek ἀπόλυσις apólysis "detachment"]) is a hormonally controlled process in the development of molting animals (ecdysozoan) and reptiles (Reptilia). One of the known hormones involved in molting animals is ecdysone . Moulting hormones can be detected in both animals and plants.

Since the cuticle (Latin for skin) in these animals cannot continuously adapt to the new proportions during growth, the old envelope , known as the exuvium , has to be shed at certain intervals . Underneath is the new, potentially larger shell, which hardens after a short time using sclerotin and can fulfill its protective function. In the time until hardening, however, the animals are defenseless and increasingly exposed to the danger of falling victim to predators. On the other hand, the old shell also sheds parasites that need a certain amount of time to penetrate the skin. With water fleas it has been observed that they can avoid infection by the bacteria Pasteuria ramosa , which pierces their skin , if they shed their skin within twelve hours of contact and thus quasi shake off the bacteria. With beetle larvae, such as the larvae of the flour beetle is after molting chitin incorporated into the new skin. The freshly moulted caterpillars still contain little chitin. The new exoskeleton, which limits growth, forms within a short time after molting.

In most insects , which therefore also have to molt, a change in shape ( metamorphosis ) is associated with the individual molting . The last moult at which the adult insect ( imago ) hatches is called the imaginal moult .

In the case of arachnids , which hatch from the egg with all the characteristics and do not undergo any metamorphosis, the last moult is called adult moult. After the adult molt, the animals are sexually mature. Previously severed limbs are renewed during the moult, but not completely and the regeneration of extremities can take several moults.

In reptiles, another horny layer forms under the horny layer through cornification . Proteolytic enzymes are released between both layers , which leads to the detachment of the old horny layer.

Web links

Commons : Ecdysis  - collection of images, videos and audio files

Remarks

  1. ↑ Apolysis. In: Lexicon of Biology. Spektrum Akademischer Verlag, Heidelberg, 1999, accessed on May 13, 2018 : "Apolyse w [from Greek apolysis = detachment], molting."
  2. ↑ H. Hoffmeister, C. Rufer, H. Ammon: Excretion of Ecdysone by Insects. In: Z Naturforsch B. 20, Feb 1965, pp. 130-133, PMID 14345159 .
  3. ↑ T. Takemoto, S. Ogawa, N. Nishimoto, H. Hoffmeister: Steroids with molting hormone activity from animals and plants. In: Z Naturforsch B. 22, No. 6, Jun 1967, pp. 681-682, PMID 4384503 .
  4. ↑ Moulting shakes off parasites. on: science.ORF.at , April 11, 2012.
  5. ↑ Rainer F. Foelix: Biology of the spiders. Georg Thieme Verlag, Stuttgart 1979, ISBN 3-13-575801-X .
  6. ↑ Thomas Steidl, Michael Hartmann: Skin diseases in reptiles. In: Small Animal Medicine. No. 4/2012, pp. 180-185.