BIOL 4105 : Life Cycles Exam 3
Document Summary
Miracidium transform into sporocyst in the wall of the intestines within 4 hours. Sporocyst gives rise to rediae within 17 days. Rediae produce 5 50 cercaria with eye spots. Released cercaria hang upside down in water, slowly sink to bottom, swim back up, and try to contact a sutitable host (fish) Cercaria infects the fish by burrowing through skin. Cercaria encysts as a metacercaria in scale or muscle. Metacercaria excysts in duodendum and migrates to liver where it crawls up the bile duct. Adults pass eggs into bile duct which opens into the intestines. Miracidium penetrates gut wall and transforms to mother sporocysts in digestive gland. Mother sporocysts produce daughter sporocysts that produce cercaria. Cercaria accumulate in snail lung (mantle cavity), irritating snail tissues (formation of slime ball after 3 months) Slime ball (containing about 500 cercaria each) expelled by snail into environment.
