Water permeability in selected decapod crustacea

Abstract

1. 1. Water influx constants for four decapods were calculated. (a) Macropipus depurator Sea water 2.39±0.71 hr −1 (b) Carcinus maenas Sea water 0.79±0.17 hr −1 70% sea water 0.78±0.14 hr −1 40% sea water 0.72±0.08 hr −1 (c) Palaemonetes varians 120% sea water 0.64±0.25 hr −1 70% sea water 0.64±0.12 hr −1 10% sea water 0.55±0.16 hr −1 (d) Astacus fluviatilis Fresh water 0.20±0.03 hr −1 2. 2. The brackish-water species Carcinus maenas and Palaemonetes varians cannot significantly alter their integumental water permeability. 3. 3. Urine volumes, predicted on a water diffusion basis, are two to four times lower than measured urine volumes. 4. 4. Internal water of Carcinus maenas and Macropipus depurator exchanges with the external medium as a two-pool system.