SWIMMING AND FEEDING BY THE SCYPHOMEDUSA CHRYSAORA-QUINQUECIRRHA

The semaeostome scyphomedusa, Chrysaora quinquecirrha (Desor, 1848), i s an abundant and important planktonic predator in estuaries and coast al waters of the eastern USA during the summer. We videotaped free-swi mming medusae in the laboratory and in the field in order to determine the relationship between swimming motions and prey encounter with cap ture surfaces. Medusae were collected from the Choptank River (Chesape ake Bay) in September 1992 and in the Niantic River, Connecticut, USA in July 1994. We used newly hatched Artemia sp. nauplii and fluorescei n dye to trace water motions around swimming medusae. Swimming results in a pulsed series of toroids which travel along the medusan oral arm s and tentacles. Prey are entrained in this flow and the location of n aupliar encounter was influenced by the phase of the pulsation cycle d uring which entrainment occurred. Flow-field velocities, measured by t racking particles adjacent to the bell margin during contraction, incr eased with bell diameter.