One of the many characteristics that separate mammals on the one hand and birds, along with their reptilian relatives, on the other, is the presence of numerous skin glands. Most birds have but a single gland, located on the top of the tail, that produces chemicals helping to maintain feather condition. In part, preening in birds involves the deployment of these substances onto the feathers.
In contrast to birds and reptiles, mammals are loaded with skin glands.
Using ourselves as examples, sweat glands occur in tremendous numbers, helping us to
remain cool in hot weather. Remember the old advertisement, "ring around the
collar"? Courtesy of sebaceous glands, glands that produce oils that help keep
skin supple and hair conditioned. And deodorants? Designed to conceal the products of
apocrine glands, those pesky skin glands that become active at puberty, sending social
signals found so embarrassing in our culture that society does its best to conceal
them. And let's not forget the glands that are ubiquitous in furred creatures and,
of course, give the mammals their name: the milk-producing mammary glands.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.