J.Comput.Physiol. A 187, 313-322, 2001
H.E. Dechant¹, F.G. Rammerstorfer² and F.G. Barth¹
¹Institute of Zoology,
University of Vienna, Vienna, Austria
²Institute of Lightweight Structures and Aerospace Engineering,
TU Wien, Vienna, Austria
Striving towards an in depth understanding of stimulus transformation in
arthropod tactile hairs, we studied the mechanical events associated with
A finite element model was developed taking a tarsal tactile hair of the
spider Cupiennius salei as an example.
Considering hair diameter, wall thickness, and curvature, the hair is
subdivided into six reagions each with its specific mechanical properties.
When the hair is touched from above with a flat surface oriented parallel to
the tarsus the point of stimulus contact moves towards the hair base with
increasing load and hair deflection.
Thereby the effective lever arm is reduced protecting the hair against breaking
near its base.
At the same time the mechanical working range of the hair increases implying
higher mechanical sensitivity for small deflections (about 5x10^-5 N/°)
than for large deflections (about 1x10^-4 N/°).
The major stresses within the hair shaft are axial stresses due to bending.
The poition of stress maxima moves along the shaft with the movement of the
Remarkably, the amplitude of this maximum (about 1x10^5 N/m²) hardly
changes with increasing loading force due to the way the hair shaft is
deflected by the stimulus.