Abstract
The respiratory rate of the brackish water shrimp Crangon vulgaris (Fabricius) was found to be lowest in the intermoult stages C - D1, and the rate increased by a factor of 2.5 up to the proecdysis stage DJ and the postecdysis stage A. At the moult (ecdysis) a short and violent outburst of activity when the old exoskeleton was thrown off increased the oxygen consumption still more. The increased respiration before and after ecdysis is explained by a higher permeability which leads to more work in the regulation of the inner milieu of the animal.