North American beaver large, webbed hind feet. The unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane which allows the beaver to see under water. The nostrils and ears are sealed while submerged. A thick layer of fat under its skin insulates the beaver from its coldwater environment. The beaver's fur consists of long, coarse outer hairs and short, fine inner hairs (see Double coat). The fur has a range of colors, but usually is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur.
Castoreum Noire, Lancôme Caractère, Hechter Madame, Givenchy III, Shalimar, and many "leather" themed compositions. In the United States, the Food and Drug Administration lists castoreum extract as a generally recognized as safe (GRAS) food additive. In 1965, the Flavor and Extract Manufacturers Association's GRAS program (FEMA 2261 and 2262) added castoreum extract and castoreum liquid. Product ingredient lists often refer to it simply as a "natural flavoring." While it is mainly used in foods and beverages as part of a substitute vanilla flavor, it is less commonly used as a part of a raspberry or strawberry flavoring. The annual industry consumption