title: Micro- and nano-structural details of a spider's filter for substrate vibrations: relevance for low-frequency signal transmission.
abstract: The metatarsal lyriform organ of the Central American wandering spider Cupiennius salei is its most sensitive vibration detector. It is able to sense a wide range of vibration stimuli over four orders of magnitude in frequency between at least as low as 0.1 Hz and several kilohertz. Transmission of the vibrations to the slit organ is controlled by a cuticular pad in front of it. While the mechanism of high-frequency stimulus transfer (above ca 40 Hz) is well understood and related to the viscoelastic properties of the pad's epicuticle, it is not yet clear how low-frequency stimuli (less than 40 Hz) are transmitted. Here, we study how the pad material affects the pad's mechanical properties and thus its role in the transfer of the stimulus, using a variety of experimental techniques, such as X-ray micro-computed tomography for three-dimensional imaging, X-ray scattering for structural analysis, and atomic force microscopy and scanning electron microscopy for surface imaging. The mechanical properties were investigated using scanning acoustic microscopy and nanoindentation. We show that large tarsal deflections cause large deformation in the distal highly hydrated part of the pad. Beyond this region, a sclerotized region serves as a supporting frame which resists the deformation and is displaced to push against the slits, with displacement values considerably scaled down to only a few micrometres. Unravelling the structural arrangement in such specialized structures may provide conceptual ideas for the design of new materials capable of controlling a technical sensor's specificity and selectivity, which is so typical of biological sensors.
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors: Maxim
authors: M
authors: Erko
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors: Osnat
authors: O
authors: Younes-Metzler
authors: European Synchrotron Radiation Facility, 38043 Grenoble, France.
authors: Alexander
authors: A
authors: Rack
authors: Charite, Berlin Brandenburg Center for Regenerative Therapies, Julius Wolff Institute, 13353 Berlin, Germany.
authors: Paul
authors: P
authors: Zaslansky
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors: Seth L
authors: SL
authors: Young
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors: Garrett
authors: G
authors: Milliron
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors: Marius
authors: M
authors: Chyasnavichyus
authors: Department of Neurobiology, Faculty of Life Sciences, University of Vienna, 1090 Vienna, Austria.
authors: Friedrich G
authors: FG
authors: Barth
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors: Peter
authors: P
authors: Fratzl
authors: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors: Vladimir
authors: V
authors: Tsukruk
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany.
authors: Igor
authors: I
authors: Zlotnikov
authors: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Research Campus Golm, 14424 Potsdam, Germany yael.politi@mpikg.mpg.de.
authors: Yael
authors: Y
authors: Politi
mesh_terms: D000162:Acoustics; D000818:Animals; D017753:Ecosystem; D005260:Female; D021621:Imaging, Three-Dimensional; D008465:Mechanoreceptors; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D049329:Nanostructures / Q000737:chemistry*; D055095:Optics and Photonics; D010812:Physical Stimulation; D012542:Scattering, Radiation; D013112:Spiders / Q000502:physiology*; D017356:Synchrotrons; D014732:Vibration; D055114:X-Ray Microtomography; D014965:X-Rays
keywords: chitin; mechanosensing; spiders
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