Sensillum

{{Short description|Sensory organ of arthropods}}

A sensillum (plural sensilla) is an arthropod sensory organ protruding from the cuticle of exoskeleton, or sometimes lying within or beneath it. Sensilla appear as small hairs or pegs over an individual's body. Inside each sensillum there are two to four sensory neurons. These neurons, or receptors, gather information about environment the arthropod is in:{{cite book|last1=Steinbrecht|first1=Rudolf Alexander|title=Ciba Foundation Symposium 200 - Olfaction in Mosquito-Host Interactions |year=2007|chapter=Structure and Function of Insect Olfactory Sensilla|series=Novartis Foundation Symposia |volume=200 |pages=158–183|doi=10.1002/9780470514948.ch13|pmid=8894297 |isbn=9780470514948 |issn=1935-4657}}

• Chemoreceptors (i.e. trichoid, basionic, coeloconic, placodea)
• Mechanoreceptors (e.g.: bristle sensilla, campaniform sensilla, hair plates, chordotonal neurons)
• Thermoreceptors
• Hygroreceptors

Most sensilla are specially shaped according to the type of information they are gathering.

In spiders, slit sensilla are used to detect substrate vibrations, while trichobothria are used to detect air-borne vibrations.{{cite journal |last1=Zhang |first1=Changchao |last2=Zhang |first2=Junqiu |last3=Chen |first3=Daobing |last4=Meng |first4=Xiancun |last5=Liu |first5=Linpeng |last6=Wang |first6=Kejun |last7=Jiao |first7=Zhibin |last8=Sun |first8=Tao |last9=Wang |first9=Dakai |last10=Niu |first10=Shichao |last11=Han |first11=Zhiwu |last12=Ren |first12=Luquan |title=Crack-based and Hair-like Sensors Inspired from Arthropods: A Review |journal=Journal of Bionic Engineering |date=1 September 2020 |volume=17 |issue=5 |pages=867–898 |doi=10.1007/s42235-020-0092-6 |s2cid=225398670 |language=en |issn=2543-2141|doi-access=free }}