Moult encyclopedia topics

Examples

Species	Item shed	Timing	Known as	Notes
Dogs and other canids	Hair (Fur)	Semi-annually, spring and fall	Shedding	Seasonal temperature variations influence shedding; some shed all year, some shed specifically twice a year.
Snakes	Skin	Regularly, when old skin is outgrown	Moulting	Snakes will rub against rocks 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.

Specific species notes

Birds


A Loggerhead Shrike in mid-moult (left) compared to one with regular plumage (right).

In birds, moulting is the periodic replacement of feathers by shedding old feathers while producing new ones. Feathers are dead structures at maturity, and they become gradually worn down and need to be replaced. Adult birds moult at least once a year, though many moult twice, and a few three times. It is a comparatively slow process, as a bird never sheds all its feathers at once; it must keep enough of its feathers to regulate its body temperature and repel moisture. The amount of shed feathers varies. In some moulting periods, a bird may renew only the feathers on the head and body, shedding the wing and tail feathers during a later moulting period. Some species of wild bird become flightless during an annual "wing moult" and must seek protected habitat with a reliable food supply during that time. A moulting bird should never have any bald spots. If a pet bird has any bald spots, the bird should be taken to an avian veterinarian to search for possible causes for the baldness, which may include giardiasis, mites, or feather-plucking.

The process of moulting in birds is as follows: First, the bird begins to shed some old feathers, then pin feathers grow in to replace the old feathers. As the pin feathers become full feathers, other feathers are shed. This is a cyclical process that occurs in many phases. In general, a moult begins at a bird's head, progresses down the body to its wings and torso, and finishes with the tail feathers. It is usually symmetrical, with feather loss equal on each side of the body. Because feathers make up 4-12 percent of a bird's body weight, it takes a large amount of energy to replace them. For this reason, moults are frequently timed to occur right after the breeding season, but while food is still abundant. The plumage produced during this time is called postnuptial plumage.

Canidae

The Canidae family is divided into the "true dogs" (or canines) of the tribe Canini and the "foxes" of the tribe Vulpini. See also: Dogs and other canids routinely shed their fur twice a year, in the spring and fall.

Seasonal temperature variations influence shedding; some shed all year, some shed specifically twice a year.

List of dogs who typically have little to no shedding:

Affenpinscher	Basenji	Bedlington Terrier	Begamasco	Bichon Frise	Bolognese
Brussels Griffon	Chinese Crested	Chinese Shar-Pei	Coton De Tulear	Dandie Dinmont Terrier	Giant Schnauzer
Havanese	Irish Water Spaniel	Lakeland Terrier	Lhasa Apso	Maltese	Miniature Schnauzer
Polish Land Sheepdog	Poodle	Portuguese Water Dog	Puli	Pumi	Shih Tzu
Soft-Coated Wheaten Terrier	Standard Schnauzer	Welsh Terrier	West Highland White Terrier	Wirehaired Pointing Griffon	Yorkshire Terrier

This may not be complete, but is a good general reference "See Go Pets for Ref"

Reptiles

The most familiar example of moulting in reptiles is when snakes "shed their skin". This is usually achieved by the snake rubbing its head against a hard object, such as a rock (or between two rocks) or piece of wood, causing the already stretched skin to split. At this point, the snake continues to rub its skin on objects, causing the end nearest the head to peel back on itself, until the snake is able to crawl out of its skin, effectively turning the moulted skin inside-out. This is similar to how you might remove a sock from your foot by grabbing the open end and pulling it over itself. The snake's skin is often left in one piece after the moulting process. Conversely, lizards' skins fall off in pieces.

Arthropods

In arthropods, such as insects, arachnids and crustaceans, moulting is the shedding of the exoskeleton (which is often called its shell), typically to let the organism grow. This process is called ecdysis. Ecdysis is necessary because the exoskeleton is rigid and cannot grow like skin. The new exoskeleton is initially soft but hardens after the moulting of the old exoskeleton. The old exoskeleton is referred to as an "exuvium" (or exuvia).