Life cycle of the suctorian ciliate Ephelota plana attached to the krill Euphausia pacifica

The hypothesis that life cycle of an epibiotic suctorian ciliate Ephelota plana is adapted to the molt cycle of the krill Euphausia pacifica collected in Saanich Inlet, Canada was evaluated. The infestation prevalence of E. plana and the number of individuals attached increased from postmolt stage to premolt stage of E. pacifica, and concurrently cell growth of E. plana was observed. Budding individuals of E. plana first appeared at early premolt stage and increased to 21% at late premolt stage. Thus the life cycle of E. plana seems to be adapted to the molt cycle of E. pacifica.