Journal of Comparative Physiology A

, Volume 166, Issue 5, pp 633–642 | Cite as

Coxal hair plates in spiders: physiology, fine structure, and specific central projections

  • Ernst-August Seyfarth
  • Werner Gnatzy
  • Klaus Hammer


Coxal hair-plate sensilla in the spider Cupiennius salei are described with respect to their innervation, central projection pattern, electrical response to mechanical stimulation, and putative behavioral function.
  1. 1.

    Hair plates, each comprising 25–70 hairs, are situated on the ventrolateral leg coxae close to the prosomal joint; during coxal movements they are deflected by the bulging joint membrane. Each plate hair is innervated by one sensory cell.

  2. 2.

    Threshold sensitivity lies at 0.5° to 1° of hair deflection. Only distalward deflection excites. During maintained deflections the spike rate declines slowly. These hairs differ from hair sensilla of insects in that we measure no ‘standing potential’, nor do we measure a ‘receptor potential’ accompanying a mechanical stimulus.

  3. 3.

    The central projection areas of both hair plates are limited to neuropil of the ipsilateral neuromere.

  4. 4.

    Natural stimulus situation and the spike response to maintained deflection suggest that these hairs are used in proprioception and graviception. Yet behavioral changes following selective hair-plate ablations are not very pronounced. Unilateral removal of hair-plates produced significant increases in average body height in 7 of 10 animals, while the angular orientation of the long body axis with respect to gravity remained unchanged after hair-plate removal.


Key words

Cuticular hair sensilla Sensory physiology Fine structure Central projections Spiders 



central nervous system


transepithelial potential difference


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • Ernst-August Seyfarth
    • 1
  • Werner Gnatzy
    • 1
  • Klaus Hammer
    • 1
  1. 1.Zoologisches Institut der J.W. Goethe-UniversitätFrankfurt am Main 11Germany

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