Moulting (ormolting) is the manner in which an animal routinely casts off part of its body (usually the outer layer or covering) at particular times of year, or at specific points in its life cycle. Moulting is also known assloughing,shedding, or for some species,ecdysis.
Moulting can involve theepidermis (skin), andhair,fur,wool, or other external layer. In some species, other body parts may be shed, for example,wings in someinsects. Examples include oldfeathers inbirds, oldhairs inmammals (especiallydogs and othercanidae), oldskin inreptiles, and the entireexoskeleton inarthropods.
| Species | Item shed | Timing | Known as | Notes |
|---|---|---|---|---|
| Chickens | Feathers | Usually autumn | Moulting | Chickens generally stop laying eggs before their moulting begins, until their new set of feathers has grown back.[1][2] |
| Dogs and othercanids | Hair (Fur) | Semi-annually, spring and fall (autumn) | Shedding Moulting | Moulting in canids, as in all mammals,[3] is thought to be due to fluctuations in the amount ofmelatonin secreted by theirpineal gland in response to seasonal sunlight variations. It has nothing to do with seasonal temperature variations. This seasonality in 'shed pattern' is most obvious in Arctic breeds of dogs that shed twice a year;[4] other breeds now shed year round. |
| Snakes | Skin | Regularly, when old skin is outgrown | Moulting | Snakes will rub against rough surfaces to shed their skin. |
| Lizards | Skin | Regularly, when old skin is outgrown | Moulting | Lizards consume their shed skin for calcium, grooming, and other nutrients |
| Hermit crabs | Exoskeleton | Regularly, when the carapace is outgrown | Moulting | Land hermit crabs bury themselves for many weeks while they moult and consume their exoskeleton. |
| Amphibians | Skin | Regularly | Moulting | Salamanders and frogs shed their skins regularly, and often eat it. |
Inarthropods, such asinsects,arachnids andcrustaceans, moulting is the shedding of theexoskeleton (orshell).
This process of moulting is calledecdysis. It is the defining feature of a whole group ofinvertebrates, thecladeEcdysozoa.[5] This group includes thearthropods,nematodes,velvet worms,horsehair worms,rotifers,tardigrades andCephalorhyncha.[6] Since the cuticles of these animals often forms an inelasticexoskeleton, it is shed during growth and a new, larger covering is formed.[5] Amongst fossils,trilobites andeurypterida used ecdysis.
Ecdysis is part of the whole process ofmetamorphosis. The different stages (called 'instars') and the development of new 'apparatus' (such as sense organs) is necessary as the creature moves from one form to another. The new exoskeleton is initially soft but hardens after the moulting of the old exoskeleton.
