Flow and prey capture by the scyphomedusa Phyllorhiza punctata von Lendenfeld, 1884

The mechanical basis of prey capture and behaviour of Phyllorhiza punctata von Lendenfeld, 1884, as with most members of the Order Rhizostomeae, has not been described. Free-swimming medusae were videotaped in order to quantitatively describe the feeding process of P. punctata. Kinematic data demonstrated that adult medusae were surrounded by relatively high Re (10(2)-10(3)) flows while swimming. Therefore, momentum dominated these flows and the motions of particles entrained in the fluid surrounding swimming P. punctata. Artemia salina nauplii entrained within these flows contacted two principle capture surfaces: the oral arm cylinder and the underside of the subumbrellar surface. Prey were ingested by small polyp-like mouthlets located on these surfaces. Ingestion followed capture at these sites. P. punctata's body morphology is highly modified to channel flows into these capture surfaces and feeding is dependent upon this pattern. Swimming activity, and hence the creation of flows used for prey capture, is continuous, as is feeding, and plays a central role in this medusa's foraging behaviour.