Traction reinforcement in prehensile feet of harvestmen (Arachnida, Opiliones)

Jonas O. Wolff*, Chantal Wiegmann, Christian S. Wirkner, Alexander Koehnsen, Stanislav N. Gorb

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Prehensile and gripping organs are recurring structures in different organisms that enhance friction by the reinforcement and redirection of normal forces. The relationship between organ structure and biomechanical performance is poorly understood, despite a broad relevance for microhabitat choice, movement ecology and biomimetics. Here, we present the first study of the biomechanics of prehensile feet in long-legged harvestmen. These arachnids exhibit the strongest sub-division of legs among arthropods, permitting extreme hyperflexion (i.e. curling up the foot tip). We found that despite the lack of adhesive foot pads, these moderately sized arthropods are able to scale vertical smooth surfaces, if the surface is curved. Comparison of three species of harvestmen differing in leg morphology shows that traction reinforcement by foot wrapping depends on the degree of leg sub-division, not leg length. Differences are explained by adaptation to different microhabitats on trees. The exponential increase of foot section length from distal to proximal introduces a gradient of flexibility that permits adaptation to a wide range of surface curvature while maintaining integrity at strong flexion. A pulley system of the claw depressor tendon ensures the controlled flexion of the high number of adesmatic joints in the harvestman foot. These results contribute to the general understanding of foot function in arthropods and showcase an interesting model for the biomimetic engineering of novel transportation systems and surgical probes.

Original languageEnglish
Article numberjeb192187
Pages (from-to)1-6
Number of pages6
JournalJournal of Experimental Biology
Volume222
Issue number3
DOIs
Publication statusPublished - 1 Feb 2019

Bibliographical note

Copyright the Author(s) 2019. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • attachment
  • friction
  • adhesion
  • arthropod leg
  • wrap
  • locomotion

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