Digital Microstructure in Ecologically Diverse Sympatric Microhylid Frogs, Genera Cophixalus and Sphenophryne (Amphibia, Anura), From Papua-New-Guinea

Dm, Green; Mp, Simon

doi:10.1071/zo9860135

Cited by 29 publications

(22 citation statements)

References 14 publications

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“…The fibrils are sectioned into highly ordered hexagonal bundles (Lin, 2008). These bundles, described first by Ernst (1973a,b); Welsh et al (1974) and studied later by many others (Green, 1979;McAllister and Channing, 1983;Green and Simon, 1986) are separated by canal-like grooves. More recent studies have been carried out by Hanna and Barnes (1991) and Barnes et al (2005Barnes et al ( , 2006.…”

Section: Tree Frogmentioning

confidence: 96%

Biological materials: A materials science approach

Meyers

Chen

López

et al. 2011

Journal of the Mechanical Behavior of Biomedical Materials

168

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Section: Tree Frogmentioning

confidence: 96%

Biological materials: A materials science approach

Meyers

Chen

López

et al. 2011

Journal of the Mechanical Behavior of Biomedical Materials

168

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“…2c). Toe pads thus possess an outer layer consisting of a hexagonal array of flat-topped cells separated by mucus-filled grooves, as in other tree frog species (Welsch et al, 1974;Green, 1979;McAllister and Channing, 1983;Green and Simon, 1986;Hertwig and Sinsch, 1995;Mizuhira, 2004). Fig.…”

Section: Toe Pad Ultrastructure In Litoria Caeruleamentioning

confidence: 99%

Ultrastructure and physical properties of an adhesive surface, the toe pad epithelium of the tree frog, Litoria caerulea White

Scholz

Barnes

Smith

et al. 2009

Journal of Experimental Biology

108

118

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SUMMARYKnowledge of both surface structure and physical properties such as stiffness and elasticity are essential to understanding any adhesive system. In this study of an adhesion surface in the tree frog, Litoria caerulea White, a variety of techniques including atomic force microscopy were used to investigate the microstructure and properties of an epithelium that adheres through wet adhesion. Litoria toe pads consist of a hexagonal array of flat-topped epithelial cells, separated by mucus-filled channels. Under an atomic force microscope, this ʻflatʼ surface is highly structured at the nanoscale, consisting of a tightly packed array of columnar nanopillars (described as hemidesmosomes by previous authors), 326±84 nm in diameter, each of which possesses a central dimple 8±4 nm in depth. In fixed tissue (transmission electron microscopy), the nanopillars are approximately as tall as they are broad. At the gross anatomical level, larger toe pads may be subdivided into medial and lateral parts by two large grooves. Although the whole toe pad is soft and easily deformable, the epithelium itself has an effective elastic modulus equivalent to silicon rubber (mean E eff =14.4±20.9 MPa; median E eff =5.7 MPa), as measured by the atomic force microscope in nanoindentation mode. The functions of these structures are discussed in terms of maximising adhesive and frictional forces by conforming closely to surface irregularities at different length scales and maintaining an extremely thin fluid layer between pad and substrate. The biomimetic implications of these findings are reviewed.

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“…Experiments on elastomer films with defined patterns of incisions yielded fracture energies that were more than 20 times higher than those measured on unstructured films of the same material [48]. The structured topology of the tree frog's toe pad consists of an array of hexagonal cells, separated by channels [4,5,52]. As each of the cells makes intimate contact with the substrate [53], one can expect that this microstructure will continuously enforce crack propagation arrest and re-initiation during toe pad peeling [48,54].…”

mentioning

confidence: 99%

Sticking like sticky tape: tree frogs use friction forces to enhance attachment on overhanging surfaces

Endlein

Samuel

et al. 2013

J. R. Soc. Interface.

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To live and clamber about in an arboreal habitat, tree frogs have evolved adhesive pads on their toes. In addition, they often have long and slender legs to facilitate not only long jumps, but also to bridge gaps between leaves when climbing. Both adhesive pads and long limbs are used in conjunction, as we will show in this study. Previous research has shown that tree frogs change from a crouched posture (where the limbs are close to the body) to a sprawled posture with extended limbs when clinging on to steeper inclines such as vertical or overhanging slopes. We investigated this change in posture in White's tree frogs (Litoria caerulea) by challenging the frogs to cling onto a tiltable platform. The platform consisted of an array of 24 three-dimensional force transducers, which allowed us to measure the ground reaction forces of the frogs during a tilt. Starting from a crouched resting position, the normal forces on the forelimbs changed sign and became increasingly negative with increasing slope angle of the platform. At about 1068 + 128, tilt of the platform the frogs reacted by extending one or two of their limbs outwards. At a steeper angle (1318 + 118), the frogs spread out all their limbs sideways, with the hindlimbs stretched out to their maximum reach. Although the extension was strongest in the lateral direction, limbs were significantly extended in the fore-aft direction as well. With the extension of the limbs, the lateral forces increased relative to the normal forces. The large contribution of the in-plane forces helped to keep the angle between the force vector and the platform small. The Kendall theory for the peeling of adhesive tape predicts that smaller peel angles lead to higher attachment forces. We compare our data with the predictions of the Kendall model and discuss possible implications of the sliding of the pads on the surface. The forces were indeed much larger for smaller angles and thus can be explained by peeling theory.

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Digital Microstructure in Ecologically Diverse Sympatric Microhylid Frogs, Genera Cophixalus and Sphenophryne (Amphibia, Anura), From Papua-New-Guinea

Cited by 29 publications

References 14 publications

Biological materials: A materials science approach

Biological materials: A materials science approach

Ultrastructure and physical properties of an adhesive surface, the toe pad epithelium of the tree frog, Litoria caerulea White

Sticking like sticky tape: tree frogs use friction forces to enhance attachment on overhanging surfaces

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