Scent glands are parts of a body that produce substances that other animals can smell. They occur in a variety of animals, and some scientists think that humans also have working scent glands. Uses of scent glands include territorial marking, sexual signals and identification of individuals.
Animals generally have five senses. These are sight, hearing, smell, touch and taste. Humans typically use sight and hearing the most to interact with each other. Other animals use their sense of smell in more important ways than humans.
In individual animals, it is the scent glands that produce substances that other animals recognize. Glands are part of the skin of an animal, where under the surface of the skin small pockets exist, which fill up with product and exude this product to the outside of the body. Different species of animal can have scent glands in different places on the body. Ring-tailed lemurs, for example, have their glands on their wrists and chest.
Male koalas have glands on the chest only. Male ringed seals exude scent substances from glands on the face, but only under certain conditions. Hyenas produce two different substances from a gland at the animal's anus. Other possible locations include on hooves, behind the ears, or on elbows.
Some types of gland produce substances that an animal can use to mark its territory. The ring-tailed lemur rubs its wrists on objects in the area it finds food in, to warn off other animals. Koalas rub the product of their chest glands on trees for the same reason.
Identification may be another possible reason for some animal's scent glands, according to some scientists. Badgers in Europe, for example, display unique variations in scents between different families. This difference in scent also appears to be the case with individual hyenas.
Aggression is another reason an animal may have scent glands. The ring-tailed lemur tends to throw gland secretions at other lemurs during a confrontation, perhaps in an effort to mark territory or claim dominance. Mink in North America also are known to release scent substances when they are involved in fights.
Unlike humans, many animal species are only interested in reproduction part of the time. Female wolves, as an example, are receptive to male wolves advances only when they are in estrus. Substances that the precaudal gland, near to the female's tail, produces may help the male wolf recognize when the female is interested in reproduction.
Humans may also communicate through scent glands. The apocrine glands of the pubic area and under the arms, which only become active in puberty, release a wax-like substance. It may be possible that humans retain the ability to smell the products of these glands and interpret them subconsciously, potentially as signs of health or even of sexual attractiveness.