Acarina
An order of small arthropods belonging to the class
Arachnida
and comprising the mites and ticks. There are over 30 000 described species, with perhaps 20 times this number still unknown, distributed worldwide in a wide variety of terrestrial and aquatic habitats. Many are free-living in soil or on vegetation, feeding on organic matter or preying on other small arthropods, while a significant number are parasites of plants and animals, including domesticated animals and humans. The adult body is generally globular or ovoid, with four pairs of legs. Unlike spiders, there is no `waist', the abdomen being fused to the more anterior prosoma. At the front of the body the ...