spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Withers, P.
Right arrow Articles by Sokol, O.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Withers, P.
Right arrow Articles by Sokol, O.

Journal of Experimental Biology, Vol 97, Issue 1 335-343, Copyright © 1982 by Company of Biologists

JOURNAL ARTICLES

Water loss and nitrogen excretion in sharp-nosed reed frogs (Hyperolius nasutus: anura, Hyperoliidae)

PC Withers, SS Hillman, RC Drewes and OM Sokol

Sharp-nosed African reed frogs, Hyperolius nasutus Gunther, are small (0.4 g) hyperoliids which have minimal rates of evaporative water loss (4.5 mg g-1 h-1; 0.3 mg cm-2 h-1) that are only 1/10 to 1/20 that of a typical frog, Hylaregilla, of comparable size (171 mg g-1 h-1, 4.8 mg cm-2 h-1). The surface-area-specific resistance to water flux of H. nasutus dorsal skin (96-257 sec cm-1) is similar to that of other 'waterproof' frogs (300-400), of cocooned frogs (40-500), and of desert reptiles (200-1400). However, H. nasutus can greatly increase the rate of evaporative water loss during radiative heat stress by mucous gland discharge, and by exposing the ventral skin. Urea is the principal nitrogenous waste product of H. nasutus and uric acid comprises less than 1% of the total nitrogen excretion for both H. nasutus and H. regilla. Other 'waterproof' frogs, in contrast, are uricotelic. Lethal dehydration requires less than two weeks in H. nasutus, despite its low surface-area-specific rate of water loss, because of its small size and concomitantly high surface-to-volume ratio. The rate of urea accumulation during dehydration was 23 mM g-1 day-1, which is sufficiently low that urea accumulation would not be lethal before the frog had succumbed to dehydrational death. Consequently, there appears to be little or no selective advantage for uricotely in small 'waterproof' frogs, such as H. nasutus.


This article has been cited by other articles:


Home page
 J. Exp. Biol.Home page
G. J. Tattersall, P. C. Eterovick, and D. V. de Andrade
Tribute to R. G. Boutilier: Skin colour and body temperature changes in basking Bokermannohyla alvarengai (Bokermann 1956)
J. Exp. Biol., April 1, 2006; 209(7): 1185 - 1196.
[Abstract] [Full Text] [PDF]

Home page
 J. Exp. Biol.Home page
H. B. Lillywhite
Water relations of tetrapod integument
J. Exp. Biol., January 15, 2006; 209(2): 202 - 226.
[Abstract] [Full Text] [PDF]


© The Company of Biologists Ltd 1982