Note:  Do not rely on this information. It is very old.


Acarina, an order of Arachnida, including a large number of small forms, in which the body is not marked off into two distinct regions by a transverse constriction. Respiration is usually effected by tracheae, minute tubes ramifying through the body and opening to the exterior. Many are parasitic. It includes the "water bear," cheese and water mites, ticks, etc.