Sensillum

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:^[1]

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.^[2]

Chemoreceptors

Chemo-reception is one of the most dominant senses in the insect kingdom. Many arthropods use chemical signals to locate food, shelter and mates.

Other invertebrates have similar sensory organs also referred to as sensilla; these consist of various papillae or ciliated areas of the cuticle connected to sensory neurons and occur in velvet worms, tardigrades and leeches.^[3]

References

^ Steinbrecht, Rudolf Alexander (2007). "Structure and Function of Insect Olfactory Sensilla". Ciba Foundation Symposium 200 - Olfaction in Mosquito-Host Interactions. Novartis Foundation Symposia. Vol. 200. pp. 158–183. doi:10.1002/9780470514948.ch13. ISBN 9780470514948. ISSN 1935-4657. PMID 8894297.
^ Zhang, Changchao; Zhang, Junqiu; Chen, Daobing; Meng, Xiancun; Liu, Linpeng; Wang, Kejun; Jiao, Zhibin; Sun, Tao; Wang, Dakai; Niu, Shichao; Han, Zhiwu; Ren, Luquan (1 September 2020). "Crack-based and Hair-like Sensors Inspired from Arthropods: A Review". Journal of Bionic Engineering. 17 (5): 867–898. doi:10.1007/s42235-020-0092-6. ISSN 2543-2141. S2CID 225398670.
^ Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. p. 508. ISBN 978-81-315-0104-7.{{cite book}}: CS1 maint: multiple names: authors list (link)

^[1]

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^ Altner, Helmut; Prillinger, Linde (1980-01-01), Bourne, G. H.; Danielli, J. F. (eds.), "Ultrastructure of Invertebrate Chemo-, Thermo-, and Hygroreceptors and Its Functional Significance", International Review of Cytology, vol. 67, Academic Press, pp. 69–139, retrieved 2022-08-13

[1] Steinbrecht, Rudolf Alexander (2007). "Structure and Function of Insect Olfactory Sensilla". Ciba Foundation Symposium 200 - Olfaction in Mosquito-Host Interactions. Novartis Foundation Symposia. Vol. 200. pp. 158–183. doi:10.1002/9780470514948.ch13. ISBN 9780470514948. ISSN 1935-4657. PMID 8894297.

[2] Zhang, Changchao; Zhang, Junqiu; Chen, Daobing; Meng, Xiancun; Liu, Linpeng; Wang, Kejun; Jiao, Zhibin; Sun, Tao; Wang, Dakai; Niu, Shichao; Han, Zhiwu; Ren, Luquan (1 September 2020). "Crack-based and Hair-like Sensors Inspired from Arthropods: A Review". Journal of Bionic Engineering. 17 (5): 867–898. doi:10.1007/s42235-020-0092-6. ISSN 2543-2141. S2CID 225398670.

[Ruppert-3] Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology, 7th edition. Cengage Learning. p. 508. ISBN 978-81-315-0104-7.{{cite book}}: CS1 maint: multiple names: authors list (link)

[4] Altner, Helmut; Prillinger, Linde (1980-01-01), Bourne, G. H.; Danielli, J. F. (eds.), "Ultrastructure of Invertebrate Chemo-, Thermo-, and Hygroreceptors and Its Functional Significance", International Review of Cytology, vol. 67, Academic Press, pp. 69–139, retrieved 2022-08-13

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