Osmotic behaviour of palaemonetes varians (leach)

Abstract

Palaemonetes varians var. microgenitor is a common brackish-water inhabitant of northern and western Europe well known for its ability to live in different concentrations of sea water. Specimens collected from brackish waters in the vicinity of Plymouth (salinity 23-29% are quite at home in the tanks of the laboratory containing normal sea water of salinity 34-35%. Estimations of osmotic pressure of blood, by Baldes' modification of Hill's thermo-electric technique from specimens kept in different concentrations of sea water, indicate that while this species is hypertonic in sea water of lower dilutions, it is definitely hypotonic in normal sea water.