SODIUM, POTASSIUM AND CHLORIDE IN SELECTED HYDROIDS

Abstract

Observations were made on Na, K and Cl contents of fresh water Hydra littoralis, brackish water Cordylophora viridissima and marine Tubularia crocea K concentrations are remarkably similar for all 3 hydroids; Na and Cl concentrations vary with environmental concentration. In dilute salt media (< 5% sea water), Na and Cl may be concentrated above environmental levels. In higher salt environments they are maintained at about 60% levels. Influx data obtained with appropriate radioactive isotopes indicate that all 3 ions are exchangeable with the environment, the usual discontinuities being evident in the Na and K influx curves. Perisarc seems to offer little resistance to movement of ions.