Meeting Abstract

P1.109  Tuesday, Jan. 4  Characterization of the Fluid Motion Generated by Upside-Down Jellyfish DOLLINGER, M*; SANTHANAKRISHNAN, A; MILLER, L; Univ. of North Carolina, Chapel Hill; Georgia Tech; Univ. of North Carolina, Chapel Hill mdollin@email.unc.edu

The medusae of the class Scyphozoa, or ‘true’ jellyfish, typically propel themselves and enhance feeding using jet propulsion and paddling. Cassiopea is a genus belonging to this class that is further characterized by a predominantly sessile lifestyle. Instead of utilizing its ring of muscle fibers to propel itself through the water while capturing prey, Cassiopea spp. contract and relax these muscle fibers in order to capture prey while remaining “upside-down” on the ocean floor. The local hydrodynamic interactions are thought to heavily affect the feeding performance of Cassiopea spp. The motions of Cassiopea spp. bells are analyzed from video imaging using DLTdv3 in MATLAB. Particle image velocimetry (PIV) was used to quantify the flow induced by the contraction and expansion of the bell. Starting and stopping vortex formation is observed during each cycle. Peak axial velocities occur near the bell margins of the Cassiopea during contraction, and a consistent train of recirculation is lost during the slower expansion. The elaborate oral arm structure of Cassiopea also prevents the formation of a coherent train of vortex rings.