Einige neue Aspekte bei der Osmoregulation von Carcinus maenas

Employing specimens of the decapod crab Carcinus maenas L. from Kiel Bay in the Baltic Sea (～13 to 18‰S) and from Helgoland in the North Sea (～32‰S), comparative studies were made on the osmotic and sodium regulations. After a 3-day exposure to low salinities of 5 or 10‰, the internal medium of the crabs from the Baltic Sea has a greater freezing point depression and a higher sodium content, than that of the North Sea crabs. In normal sea water, the blood of North Sea specimens is slightly hyperosmotic; the blood of specimens from the Baltic Sea is nearly isosmotic to the surrounding medium. Individual cross adaptations to the different habitat salinities (2 to 3 weeks) result in a reduction of the osmotic differences in specimens of the two populations; the differences do not, however, completely disappear.