Abnormal morphological changes were observed in CHO K-1 cells previously exposed to either crude or DE-52 fractionated sea nettle ( Chrysaora quinquecirrha) venom. At high doses the venom inhibited the growth of cultured cells and interfered with intracellular uridine and thymidine incorporation. Low doses of venom induced mitogenic activity in CHO K-1 cells. Partially purified venom agglutinated trypsinized rabbit erythrocytes in the presence of calcium. The venom's dermonecrotic activity and its cytotoxic and hemagglutinating activities were eluted together from a DEAE cellulose column.