Curly Coat and Rex Animals.
Most mammals naturally have straight hair. However there are a number of relatively common mutations produce hair that is variously described as kinky, curly or rex. In some cases this variation has been used to develop a new domesticated breed.
The Frillback Pigeon has tightly curling feathers on its body. This is an old breed, known to have been kept by Charles Darwin amongst others.
The 'rex' coat appears spontaneously in cat population and sometimes is is selected for and forms the basis of a recognized breed. Rex coats are often light and do not provide good protection from the cold, thus rex cats should be kept indoors.
The Cornish Rex has very short fine hair that is often curled, producing a rippled appearance (see right). The German Rex has a very similar genotype and appearance.
The Devon Rex dates from 1959, developed from a single curly-haired male kitten. The Devon Rex mutation effects the Keratin 71 gene. A different mutation of the same gene produces the hairless ("sphynx") cat. And the Devon Rex is prone to developing bald areas.
The Oregon Rex dates from around 1972 and seems to be based on a distinct third mutation.
The LaPerm cat is derived from a spontaneous mutation observed in some Oregon 'barn cats'. LaPerm kittens are often born bald.
A fairly new arrival on the curly-coat scene is the Selkirk Rex, derived from a litter born in 1987. The curly coat is inherited as a dominant gene. This variety is not widely recognized as an official breed. The Selkirk's coat has a loose curl in all hair including whiskers.
Highland cattle often develop a distinctly curly appearance, as may other heritage breed ot crosses with wild types such as bison. Long hair is characteristic of many other cattle breeds,but an actual curl may be considered a defect (e.g. in Galloways).
A curly coat gene may be emerging in chinchillas, referred to as curlies or angoras.
A number of dog breeds are known for a curly coat including the Bichon Frise, Curly-Coated Retriever, Irish Water Spaniel and Poodle. The trait may be inherited by cross-breds such as the labradoodle.
The Texel is a long-haired guinea pig with corkscrew curls.
There is a gene in American horses that causes long curly or kinky hair, most obvious when they have their longer winter coat. The animals are referred to as "Curly Horses". It has been suggested that many people with allergic responses to horses are able to ride curly horses. The horses curly coat is clearest in their winter when their coat is longer. but the curl is evident all year round in the mane, fetlocks and hair inside the ear.
In India the Manipuri Pony often has a very thick, curly coat. Traditionally used as cavalry mounts they are now popular as Polo ponies.
There are various mutation in mouse population that cause curly coat in the juvenile or adult. for example: rex and stpm.
The Mangalitsa pig is a traditional breed that dates from 1833 and is selected to put on thick layers of fat. It has profuse woolly hair that is often curly.
The Lincolnshire curly coat is a very rare breed with a particularly dense and pale coat, resembling a sheep's fleece.
The first animal referred to as "Rex" was a breed of rabbits developed in 1919. The Rex rabbit has dense, soft fur that is curly in some areas where the hair is long enough.
Rex rats were developed in 1976. The Rex gene in rats is typically dominant. however the expression of the curly coat is variable and often much stronger in pups than in adults who may show little or no curl.
The coat types of Velveteen and Harley rats also often have a degree of curl.
Many breeds of sheep have a curly fleece (e.g. Dartmoor, Shetland).
As with many other species human may have curly hair, and this trait may be under the control of a single gene.
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- Searle AG & Jude AC (1956). The 'rex' type of coat in the domestic cat. Journal of Genetics 54, 506-513. [Full Text]