They include such familiar scourges as dust mites, spider mites, scabies and chiggers, as well as a huge range of lesser-known parasites, predators, and fungivores. A number of developmental characteristics unite the Acariformes.
Development is anamorphic , meaning that body segments are added between moults.
Also, prior to moulting, the legs of the subsequent instar are formed within the body rather than within the hulls of the previous instar's legs. There are also several characteristics of acariform setae that differentiate them from other Acari. Another name for the Acariformes is the 'Actinotrichida', which refers to the fact that their setae have a layer of optically active chitin, 'actinochitin' , that is birefringent under polarized light. Trichobothria , specialized setae that are sensitive to vibrations and air currents, are found in the Acariformes but not in other mites. Other modified sensory setae unique to the Acariformes include solenidia and eupathidia .