Mites on occasion have become extreme specialists in selecting the places where they live. Take the noses of vertebrates. It may not seem much, but a wide variety of mites call it home. Mites can do different things while in the nose. Rhinoseius and some Proctolaelaps species use hummingbird noses to move from flower to flower.
The mites race up or down the bill when the bird is feeding to get in or out of the nose as they move between flowers. Nice and fast transportation but it can be tricky. If a male ends up in a flower already occupied by males of a different species they may get attacked and killed. As always make sure you get off at the right bus stop.
Dispersal is also the goal for some Halarachnidae living in seals. They live most of their lives in the lungs, but larvae will crawl up into the nose and get dispersed by sneezing. It is not sure whether they irritate the nose and make the seals sneeze or whether they just take advantage of seal sneezing. This form of dispersal is of course a bit random. For example, a paper from 1985 described a case where an ophthalmologist recovered a halarachnid mite from the eye of a patient with severe eye discomfort. The man had been watching the walrus exhibit at Sea World. Moral of the story: be aware of flying debris when visiting the seal exhibit.
Most nose-inhabiting mites are true parasites. Some chiggers (Trombiculidae) are found only in noses. So do most species of Gastronyssidae, although I have collected some skating around on the eyeball of fruitbats, and 1-2 others appear exclusive to the stomach of such bats. In birds we sometimes see a split in microhabitat: Rhinonyssidae live in the slimy parts of the nostrils, Ereynetidae skate on top of the slime, and Turbinoptidae live in the dryer section further down.
Noses are true ecosystems.
About the Author: Dr. Hans Klompen is professor in the department of Evolution, Ecology and Organismal Biology and director of the Ohio State University Acarology Collection.
Webb, J.P., Jr., Furman, D.P. & Wang, S. (1985) A unique case of human ophthalmic acariasis caused by Orthohalarachne attenuata (Banks, 1910) (Acari: Halarachnidae). Journal of Parasitology, 71 (3), 388-389.