Facial skin glands of ringed and grey seals, and their possible function as odoriferous organs

• Published in: Canadian Journal of Zoology
• Main Authors: Hardy, Margaret H., Roff, Elizabeth, Smith, Thomas G., Ryg, Morten
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1991
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Svalbard; Norway; Phoca hispida
• Online Access: http://dx.doi.org/10.1139/z91-029; http://www.nrcresearchpress.com/doi/pdf/10.1139/z91-029

Mature male ringed seals (Phoca hispida) have a very strong odour emanating from the facial region during the breeding season. The inner surface of the skin from the heads of three animals captured during the mating season revealed the distribution of closely packed, much enlarged sebaceous glands on the anterior muzzle skin and extending into the interorbital and postvibrissal regions. A histological study was made of facial skin from 22 animals of different ages and both sexes, taken from Svalbard, Norway, during the breeding season. In mature males the sebaceous glands on the face were 3–8 times larger in cross section and more actively secreting than glands on the neck. Melanin granules were concentrated in the sebum. These facial glands were also 2–10 times larger and more actively secreting than the facial glands of immature males, mature females, or immature females. The apocrine sweat glands on the face of mature males were also much larger and more active than those of the other groups. It was concluded that the greater size, secretory activity, and melanin production of the sebaceous glands of mature male ringed seals could account for the strong odour and dark colour that have been observed on the face in the breeding season. The enlarged and active apocrine sweat glands might also contribute to the odour. The facial skin of six dominant bull grey seals (Halichoerus grypus), killed during the breeding season, had sebaceous glands of intermediate size, but high activity and high melanin content in the sebum. Their apocrine sweat glands were very large and active, indicating that they also may have a role in sexual signalling.