title: Morphological studies of the toe pads of the rock frog, Staurois parvus (family: Ranidae) and their relevance to the development of new biomimetically inspired reversible adhesives.
abstract: The morphology of the toe epithelium of the rock frog, Staurois parvus (Family Ranidae), was investigated using a variety of microscopical techniques. The toe pad epithelium is stratified (four to five cell layers), the apical parts of the cells of the outermost layer being separated by fluid-filled channels. The surface of these cells is covered by a dense array of nanopillars, which also cover the surface of subarticular tubercles and unspecialized ventral epithelium of the toes, but not the dorsal epithelium. The apical portions of the outer two layers contain fibrils that originate from the nanopillars and are oriented approximately normal to the surface. This structure is similar to the pad structure of tree frogs of the families Hylidae and Rhacophoridae, indicating evolutionary convergence and a common evolutionary design for reversible attachment in climbing frogs. The main adaptation to the torrent habitat seems to be the straightness of the channels crossing the toe pad, which will assist in drainage of excess water. The presence of nanopillar arrays on all ventral surfaces of the toes resembles that on clingfish suckers and may be a specific adaptation for underwater adhesion and friction. The relevance of these findings to the development of new biomimetically inspired reversible adhesives is discussed.
authors: Max Planck Institut für Polymerforschung , Mainz , Germany.
authors: Dirk M
authors: DM
authors: Drotlef
authors: Functional Morphology and Biomechanics , University of Kiel , Kiel , Germany.
authors: Esther
authors: E
authors: Appel
authors: Functional Morphology and Biomechanics , University of Kiel , Kiel , Germany.
authors: Henrik
authors: H
authors: Peisker
authors: Functional Morphology and Biomechanics , University of Kiel , Kiel , Germany.
authors: Kirstin
authors: K
authors: Dening
authors: Max Planck Institut für Polymerforschung , Mainz , Germany.
authors: Aránzazu
authors: A
authors: Del Campo
authors: Functional Morphology and Biomechanics , University of Kiel , Kiel , Germany.
authors: Stanislav N
authors: SN
authors: Gorb
authors: Centre for Cell Engineering , University of Glasgow , Scotland , UK.
authors: W Jon P
authors: WJ
authors: Barnes
keywords: adhesive toe pad; biomimetics; cell shape; electron microscopy; functional morphology; rock frog
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