The sulfide also has toxic effect on u . unicinctus . the time that experimental populations reach 50 % mortality shortens as the sulfide concentration increasing . and the body color changes to dark 同时硫化物对单环刺?有显著的毒性作用, ?虫的半数致死时间随硫化物浓度的升高而缩短,体色亦逐渐变深。