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.
Castor and Pollux regarded as helpers of humankind and held to be patrons of travellers and of sailors in particular, who invoked them to seek favourable winds. Their role as horsemen and boxers also led to them being regarded as the patrons of athletes and athletic contests. They characteristically intervened at the moment of crisis, aiding those who honoured or trusted them. Ancient Greek authors tell a number of versions of the story of Castor and Pollux. Homer portrays them initially as ordinary mortals, treating them as dead in the "Iliad" ("... "there are two commanders I do not see, / Castor the