The skin separates man's biological self from his immediate animal and vegetable environment. It is interesting to take a "microbe's eye view" of the skin as a suitable home.
A good many arthropods successfully inhabit skin with establishment of life cycles essential to their existence. The creation of geophilic strains of fungi of man begets an idealized existence for dermatophytes capable of one form of life on the skin, and another in the soil. Some interesting problems exist with such organisms as Myco leprae, which inhabits the subepidermal skin, yet seems more closely related to soil mycobacteria than to animal pathogens. Herpesviruses, poxviruses, and papovaviruses, all have a home in the skin. Tracking down these relations shows the skin to be a part of several ecosystems, the subject which has been awkwardly styled "ecology of the skin."
The author's approach is both valid and entertaining, although from the academic standpoint