Trichobothria (singular
trichobothrium) are elongate
setae ("hairs") present in
Arachnida, various orders of
, and
that function in the detection of airborne vibrations and currents, and electrical charge.
In 1883,
Friedrich Dahl observed that they were deflected by the sound waves from a violin and labelled them 'hearing hairs'.
Morphology
Unlike the ordinary setae, which are tapered, the trichobothria have the same gauge throughout their length. They fit into the bottom of a broad and deep cup to which connects a membrane with extreme flexibility which adds an extraordinary mobility to them. The least air vibration is able to get them moving and to excite the small group of sensory cells which ensures their innervation.
Distribution
Trichobothria are present in most orders of the
Arachnida, except in
Solifugae,
Ricinulei and
Opiliones (Grassé, 1949). Although the distribution of trichobothria on the bodies of
arachnids is often used by systematists
(especially in
Scorpiones and
Pseudoscorpiones), few interordinal patterns are apparent (Shultz, 1990).
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Foelix, R.F., 1982. Biology of Spiders. Harvard University Press. Cambridge, Massachusetts, and London, England.
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Grassé, P. (1949). Traité de Zoologie: Anatomie, Systématique, Biologie / publié sous la dir. de M. Pierre-P. Grassé. tome VI, Onychophores - Tardigrades - Arthropodes - Trilobitomorphes - Chélicérates. - Masson et Cie, Paris.
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Shultz, J.W. (1990). Evolutionary Morphology And Phylogeny of Arachnida. Cladistics 6: 1-38.
