ISSN:
1432-136X
Keywords:
Ionoregulation
;
Urine output
;
Urine composition
;
Semi-terrestrial crabs, Ucides, Carcinus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The mangrove crab Ucides cordatus showed a significant reduction in its output of isosmotic urine (to 60% of submerged rates) in humid, emersed conditions when in apparent water balance. A similar, but lesser, reduction was observed in the intertidal temperature species Carcinus maenas. Some of the decrease is effected by increased water withdrawal of an isosmotic fluid in the antennal gland (inulin urine to haemolymph concentration ratio=1.27) in Ucides but most is due to the reduced filtration rate which decreases from 3.41 to 2.19 ml·100 g-1·day-1 (in Carcinus from 7.37 to 5.88). In Carcinus, inulin urine to haemolymph concentration ratios are within the range 1.34–1.41 and show significant change on emersion. Comparisons of ion and inulin clearance ratios revealed interspecific differences in renal handling of Na+ and Cl-. During emersion total Na+ efflux is markedly reduced in both species. Urinary Na+ losses are responsible for most of the efflux in Carcinus but represent only ≈50% of the total in Ucides. Significant Na+ uptake from interstitial water occurs in Ucides. REductions in ion and water loss appear to be mainly dependent on decreases in urine output (clearance rate). However, some released urine was found to accumulate in the branchial chambers in both species. Whether or not extrarenal reabsorption of ions from released urine occurs in the gill chambers in either crab species remains to be proved.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00309661
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