Summary
Rows of long, smooth hair sensilla situated on both sides of the leg coxae were examined in the spider Cupiennius salei (Ctenidae). The hair shafts point into the space between adjacent legs and are deflected when the hairs of one coxa touch the cuticle of the neighboring coxa. 1. Unlike the serrated hair shafts of the ubiquitous tactile and chemosensitive setae of spiders, these hairs are entirely smooth. At their base they are articulated in a socket with an asymmetrical groove that determines the direction of hair deflection. Hair shafts are up to 1000 μm long. The exact grouping of smooth hairs in rows is typical of the coxae for each pair of legs. 2. Unlike the other, multiply innervated cuticular sensilla of spiders, smooth hairs are supplied by only a single mechanosensitive neuron. This is confirmed by electrophysiological recordings from single hairs. Threshold deflection to elicit a spike response lies near 1°. The response to maintained, step-like stimuli declines rapidly. 3. All central endings of these hair receptors in the fused segmental ganglia are confined to dorsal neuropil of the ipsilateral neuromere. The specific arborization pattern resembles an elongated, three-pronged fork with a long central prong. Topography, natural stimulus situation, and the “phasic” response characteristic of smooth hairs suggest that spiders use these sensilla to monitor the relative distance between leg coxae during locomotion.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Babu KS, Barth FG (1984) Neuroanatomy of the central nervous system of the wandering spider, Cupiennius salei (Arachnida, Araneida). Zoomorphology 104:344–359
Bacon JP, Altman JS (1977) A silver intensification method for cobalt-filled neurons in wholemount preparations. Brain Res 138:359–363
Eckweiler W, Seyfarth E-A (1988) Tactile hairs and the adjustment of body height in wandering spiders: behavior, leg reflexes, and afferent projections in the leg ganglia. J Comp Physiol A 162:611–621
Foelix RF (1985) Mechano- and chemoreceptive sensilla. In: Barth FG (ed) Neurobiology of arachnids. Springer, Berlin Heidelberg New York, pp 118–137
Kaestner A (1924) Beiträge zur Kenntnis der Lokomotion der Arachniden. I. Araneae. Arch Naturgesch 90A:1–19
Seyfarth E-A (1985) Spider proprioception: Receptors, reflexes, and control of locomotion. In: Barth FG (ed) Neurobiology of arachnids. Springer, Berlin Heidelberg New York, pp 230–248
Seyfarth E-A, Hammer K (1988) Central projections of cuticular mechanoreceptors in spiders: the specificity of proximal leg sensilla. In: Haupt J (ed) Comptes Rendus du XIème Colloque d'Arachnologie (Colloque international europeén). TUB-Dokumentation 38, Berlin, pp 23–28
Seyfarth E-A, Eckweiler W, Hammer K (1985) Proprioceptors and sensory nerves in the leg of a spider, Cupiennius salei (Arachnida, Araneida). Zoomorphology 105:190–196
Seyfarth E-A, Gnatzy W, Hammer K (1986) Coxale Borstenfelder bei Spinnen: Sinnesphysiologie, Feinstruktur und zentrale Projektionen. Verh Dtsch Zool Ges 79:240–241
Thurm U (1962) Ableitung der Rezeptorpotentiale und Nervenimpulse einzelner Cuticula-Sensillen bei Insekten. Z Naturforsch 17 (B):285–286
Tyrer NM, Bacon JP, Davies CA (1979) Primary sensory projections from the wind-sensitive head hairs of the locust, Schistocerca gregaria. I. Distribution in the CNS. Cell Tissue Res 203:79–92
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Eckweiler, W., Hammer, K. & Seyfarth, EA. Long, smooth hair sensilla on the spider leg coxa: Sensory physiology, central projection pattern, and proprioceptive function (Arachnida, Araneida). Zoomorphology 109, 97–102 (1989). https://doi.org/10.1007/BF00312315
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00312315