Prodorsal Eyes

Mites have no head, and the capitulum is composed of only the first two segments of the body, so when they have eyes they are found on the idiosoma.  The eyes are never compound (those are found only in insects, crustaceans, and horseshoe crabs).  Instead, the eyes are composed of single ocelli, typically 1-2 (rarely 3) pairs dorso-laterally on the idiosoma above the front legs, but rarely there is also a median eye (rarely 2 eyes) that is usually located under a naso.

Eyes are common in the Prostigmata, Endeostigmata, and Opilioacarida, but absent in all Mesostigmata and in most oribatid mites, Astigmatina, and ticks.  In some Prostigmata (e.g. velvet mites with dense pelages of fur), the eyes may be raised on stalks and in many the posterior pair of eyes is structurally different from the anterior pair and sometimes referred to as the postocular structure or pustule.  In some oribatid mites, a new and unpaired light sensitive organ has been derived - the lenticulus.

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