Animal fiber

Animal fibers are natural fibers that consist largely of certain proteins. Examples include silk, hair/fur (including wool) and feathers. The animal fibers used most commonly both in the manufacturing world as well as by the hand spinners are wool from domestic sheep and silk. Also very popular are alpaca fiber and mohair from Angora goats. Unusual fibers such as Angora wool from rabbits and Chiengora from dogs also exist, but are rarely used for mass production. Not all animal fibers have the same properties, and even within a species the fiber is not consistent. Merino is a very soft, fine wool, while Cotswold is coarser, and yet both Merino and Cotswold are types of sheep. This comparison can be continued on the microscopic level, comparing the diameter and structure of the fiber. With animal fibers, and natural fibers in general, the individual fibers look different, whereas all synthetic fibers look the same. This provides an easy way to differentiate between natural and synthetic fibers under a microscope. Silk is a "natural" protein fiber, some forms of which can be woven into textiles. The best-known type of silk is obtained from cocoons made by the larvae of the silkworm Bombyx mori reared in captivity. Rearing of silks is called sericulture. Degummed fibers from B. mori are 5-10 μm in diameter. The shimmering appearance for which silk is prized comes from the fibers' triangular prism-like cross-sectional structure which allows silk cloth to refract incoming light at different angles. The length of the silk fiber depends on how it has been prepared. Since the cocoon is made of one strand, if the cocoon is unwound carefully the fibers can be very long. Spider silk is the strongest natural fiber known. The strongest dragline silk is five times stronger than steel and three times tougher than Kevlar. It is also highly elastic, the silk of the ogre-faced spider can be stretched six times its original length without damage. As of 2005, there is no synthetic material in production that can match spider silk, but it is actively being sought by the U.