The movable head is attached to the body by a hinge. The thousands of different species are worldwide in distribution and occupy diverse habitats, including plant galls, mosses, other animals, and surface litter or upper layers of the soil. One group, the water mites, has returned to an aquatic environment, both fresh and salt water. Mites eat plant or animal substances, decaying organisms, and humus, and also infest stored food products such as cheese, meat, grains, and flour. The red spider, a mite and not a spider, feeds on plants and is destructive to crops.
Many mites are parasitic on other arthropods, on mollusks, or on vertebrates.
Mange and scabies mites lay their eggs in the skin and cause irritation in man and fur-bearing animals. Other species are parasitic on the skin of birds and reptiles, and some live in the respiratory channels of birds and mammals. Chiggers, the larvae of harvest mites, transmit the organism that causes scrub typhus. Fowl mites feed on the blood of poultry. An anchoring structure in the tick's mouth enables it to embed its entire head under the skin of the host, where it sucks the host's blood.