Structural correlates of increased adhesive efficiency with adult size in the toe pads of hylid tree frogs

Smith, J. M., Barnes, W. J. P., Downie, J. R. and Ruxton, G.D. (2006) Structural correlates of increased adhesive efficiency with adult size in the toe pads of hylid tree frogs. Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, 192(11), pp. 1193-1204. (doi: 10.1007/s00359-006-0151-4)

Abstract

Tree frogs are able to climb smooth, vertical substrates using specialised toe pads which adhere via an area-based wet adhesive mechanism. Although the link between pads and arboreality in frogs is well-established, few studies have investigated the influence of morphology on adhesion. Trinidadian tree frogs from the genus Hyla are geometrically similar. There is a tendency towards comparatively reduced mass in larger species, but toe pad area increases as expected with isometry. As adhesion is area-dependent, forces are affected directly by the increase in mass relative to pad area, and there is a decrease in the ability of larger species to adhere to smooth rotation platforms. However, there is an increase in force per unit area that suggests larger species have more efficient toe pads. Toe pad structure is very similar though there are variations in the details of a number of features. Crucially, although differences in morphology appeared small they had demonstrable effects on adhesive efficiency of the pads. Epithelial cell area correlates positively with frog length and adhesive efficiency, related features of cell density and intercellular channel length correlate negatively. These findings are discussed in relation to the different forces involved in the tree frogs’ wet adhesive system.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ruxton, Professor Graeme and Downie, Professor Roger and Barnes, Dr William
• Authors: Smith, J. M., Barnes, W. J. P., Downie, J. R., and Ruxton, G.D.
• College/School: College of Medical Veterinary and Life Sciences > School of Molecular Biosciences
• Journal Name: Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology
• Publisher: Springer
• ISSN: 0340-7594
• ISSN (Online): 1432-1351
• Published Online: 08 September 2006