Chinchilla hair. Coloured scanning electron micrograph (SEM) of chinchilla hairs. Chinchillas, rodents in the family Chinchillidae, have the densest fur of any animal. Up to 70 hairs can grow from a single follicle, whereas in humans a follicle houses a single hair. The hair is also uniform, with few, if any, guard hairs, and at under 1 micrometre in diameter is approximately 500 times finer than human hair. Chinchillas are native to the Andes mountains of South America, but are kept as pets in countries worldwide.