Grazing by the jellyfish, Aurelia aurita, on microzooplankton

The medusa of the scyphozoan, Aurelia aurita, is a seasonally important predator of copepods and fish larvae in coastal waters but little is known about its grazing on microzooplanltton. Medusae preferentially remove large (≥50 μm) oligotrichs and copepod nauplii from natural microzooplankton assemblages. Clearance rates for phytoplankton, tintinnids, rotifers and polychacte larvae are usually low. In feeding experiments in which mixtures of cultured prey were used, medusae selected small non-loricate ciliates over similar-sized algae, non-loricate ciliates over tintinnids, and large non-loricate ciliates over smaller ones. Observations of feeding medusae confirmed that post-capture selection of particles is important during microphagous feeding.