QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Morris, S. Articles by Ahern, M. D. Search for Related Content PubMed PubMed Citation Articles by Morris, S. Articles by Ahern, M. D.

Journal of Experimental Biology, Vol 203, Issue 2 389-396, Copyright © 2000 by Company of Biologists

JOURNAL ARTICLES

Adaptations to a terrestrial existence in the robber crab Birgus latro L. IX. Hormonal control of post-renal urine reprocessing and salt balance in the branchial chamber

S Morris, P Greenaway, AM Adamczewska and MD Ahern
Morlab School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. smorris@nsw.bigpond.net.au

The terrestrial robber crab Birgus latro L. regulates the composition of its final excretory product (termed P) depending on the availability of dietary salt by reabsorbing ions from urine passed over the gills. Laboratory and field-based studies investigated the nature of the mechanisms of control of this branchial ion uptake. B. latro were prepared such that their branchial chambers could be perfused with artificial urine, and the rate of ion transport from the artificial urine was determined. For B. latro acclimated to drinking fresh water, the rates of Na(+) and Cl(-) uptake were more than four times those of crabs drinking 70 % sea water. Crabs were injected with either saline carrier or the same solution containing either dopamine or dibutyryl cyclic AMP (db-cAMP) (final concentration 8.7x10(-)(7 )mol l(-)(1 )haemolymph). Dopamine and db-cAMP inhibited Na(+) and Cl(-) uptake in animals acclimated to fresh water and markedly reduced their gill Na(+)/K(+)-ATPase activity. Dopamine stimulated the production of cyclic AMP within the branchial epithelial cells. Dopamine, released from the pericardial organs, acts as a primary messenger, and cyclic AMP acts as a second messenger most likely promoting phosphorylation of membrane proteins. In contrast to aquatic brachyuran crabs, ion transport in B. latro, an anomuran, is controlled via an inhibitory effect. Terrestrial crabs normally have access to fresh water and must salvage salt from their urine, and a mechanism to down-regulate a normally active uptake system seems more appropriate to their ecology. Whether the control is stimulatory or inhibitory in the various air-breathing crabs may depend on the osmoregulatory abilities of their aquatic ancestors, but in either case has significant implications for the evolution of crustaceans to life on land. Further work must establish whether terrestrial brachyuran crabs are similar to B. latro and whether this crab is unique amongst the anomuran crabs.

This article has been cited by other articles:

				D. Weihrauch, S. Morris, and D. W. Towle Ammonia excretion in aquatic and terrestrial crabs J. Exp. Biol., December 15, 2004; 207(26): 4491 - 4504. [Abstract] [Full Text] [PDF]

				S. Morris and M. D. Ahern Regulation of urine reprocessing in the maintenance of sodium and water balance in the terrestrial Christmas Island red crab Gecarcoidea natalis investigated under field conditions J. Exp. Biol., August 15, 2003; 206(16): 2869 - 2881. [Abstract] [Full Text] [PDF]

				H. H. Taylor and P. Greenaway Osmoregulation in the terrestrial Christmas Island red crab Gecarcoidea natalis (Brachyura: Gecarcinidae): modulation of branchial chloride uptake from the urine J. Exp. Biol., October 15, 2002; 205(20): 3251 - 3260. [Abstract] [Full Text] [PDF]

				S Morris Neuroendocrine regulation of osmoregulation and the evolution of air-breathing in decapod crustaceans J. Exp. Biol., January 3, 2001; 204(5): 979 - 989. [Abstract] [PDF]