Cutaneous properties of the Green and Golden Bell Frog <i>Litoria aurea</i>
1996
Buttemer, W. A. | van der Wielen, M. | Dain, S. | Christy, M.
We measured rates of evaporative water loss (EWL) in <i>Litoria aurea</i> at 25, 30, 33, and 35°C. There was a substantial rise in EWL over this range of temperatures, averaging 12.3 and 23.5 mg g<sup>-1</sup> h<sup>-1</sup> at 25 and 35°C, respectively. The rise in EWL over this temperature interval was associated with a corresponding drop in cutaneous resistance to water vapour flux (r<sub>c</sub>) which steadily declined from 6.9 to 3.5 s cm<sup>-1</sup>. The average highest r<sub>c</sub> measured for these eight frogs was 7 s cm<sup>-1</sup> which places this species amongst frogs considered to have moderately waterproof skins. We also quantified the spectral reflectance of <i>L aurea</i> dorsal skin at wavelengths between 280 and 900 nm, The skin had a peak at 550 nm which was expected for a green frog, but lacked the abrupt rise in reflectance at about 700 nm found in green leaves and some other species of green, leaf-sitting <i>Litoria</i> species. The absence of high near-infra-red reflectivity in <i>L aurea</i> is attributed to its retention of melanin as a darkening pigment instead of pterorhodin which is used instead by green, leaf-sitting Litorine and Phyllomedusine frogs showing complete crypsis with green leaves.
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