A haemolytic toxin was purified by ion-exchange chromatography and FPL
C gel filtration from the nematocysts of the jellyfish Carybdea marsup
ialis. Sheep red cells, but not human or rabbit red cells, were suscep
tible to lysis by the toxin. The toxin is a protein with an apparent m
olecular mass of about 102-107 kDa, is heat labile, highly unstable in
polar media, inactivated by reducing agents, and devoid of phospholip
ase activity. The experimental data speak in favour of a pore-forming
mechanism of toxin action.