Haemolymph pressure regulation in Porcellio laevis Latr. (Porcellionidae, Isopoda).

Hydrostatic pressure in the haemocoele in Porcellio laevis adults ranges between 3.69 to 12.92 mm Hg (50 to 175 mm H2O). Mechanism involved in haemolymph pressure regulation includes characteristic contractions of intersegmental body musculature. The effects of temperature, humidity, decapitation, destruction of thoracic ganglion, and the injection of insect Ringer and eserine into the haemocoele on intersegmental muscular contractions were studied. The significance of these findings is discussed.