Overview

Ticks have a variety of peripheral organs. Most common are setae, hair-like structures. Further are non-porous, porous setae, multiporous sensilla and tip pore sensilla.
Tick sensory organs, the sensilla organs, may be classified by function: chemosensilla, mechanosensilla, photosensilla, thermosensilla and multifunctional sensilla.

Chemosensilla

Two major categories are known: olfactory sensilla and gustatory sensilla.
Chemosensilla typically consist of seta, socket, neurons, thecogen, scolopale, the inner trichogen and the outer tormogen or auxiliary cells.

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Mechanosensilla

Mechanosensilla are sensilla that contain neurotubular cytoskeletons.
The most common mechanosensilla in ticks are the setiform sensilla which occur over the capitulum, body surface, and legs.
Mechanosensilla respond to physical contact, i.e. touch.
Often, mechanosensilla occur as parts of multifunctional sensilla, i.e., combined with chemoreceptive dendrites.

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Haller's Organ

The Haller's organ is found on the dorsal surface of the tarsi of leg. It consists of the posterior capsule and the anterior pit. The major function of this complex organ is believed to be olfaction.

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