Skunks are moderately small mammals, usually with black-and-white fur, belonging to the family Mephitidae and to the order Carnivora. There are 11 species of skunks, which are divided into four genera: Mephitis (hooded and striped skunks, two species), Spilogale (spotted skunks, two species), Mydaus (stink badgers, two species), and Conepatus (hog-nosed skunks, five species). The best-known, most distinctive, and often most notorious feature of the skunks is the great development of their anal scent glands, which they can use as a defensive weapon. Skunks have two glands, on either side of the anus, that produce a mixture of sulfur-containing chemicals (methyl and butyl thiols) that has a highly offensive smell. The odor of the fluid is strong enough to ward off bears and other potential attackers, and can be difficult to remove from clothing. Muscles located next to the scent glands allow them to spray with high accuracy as far as 2 to 3 metres (7 to 10 ft). The smell aside, the spray can cause irritation and even temporary blindness, and is sufficiently powerful to be detected by even an insensitive human nose anywhere up to a mile downwind. Skunks are reluctant to use their smelly weapon, as they carry just enough of the chemical for five to six uses - about 15 cc - and require some ten days to produce another supply.